Ocean Science Experiments Guide by OceanConservationTrust

Ocean Sciencewith the OCT

Classroom Experiments inspired by British Science Week 2025

OCT Learning Programme

The Ocean Conservation Trust learning team provide an exciting and interactive Learning Programme, using the Ocean to deliver all subjects of the curriculum. Our immersive opportunities cater to students of all levels, inspiring approximately 30,000 yearly to connect with and protect the Ocean. To find out more about our programme and upcoming events, visit https://oceanconservationtrust.org/oceanexperiences/education/.

Free Activity Plans

For British Science Week 2025, allow your class to dive into the theme of ‘Change and Adapt’ with a focus on the physical and chemical changes in the Ocean.

This free set of activity plans is packed with engaging practical activities to take place in the classroom to support this year’s theme. Each plan is designed to help teachers lead accessible, hands-on activities that illustrate marine science concepts, and link to how life in the Ocean have adapted to these conditions.

These resources have been tailored to meet the working scientifically requirements of the National Curriculum. This makes them an ideal addition to your lesson plans in the lead up to or during British Science Week, or to be used all year round!

Investigating the density of saltwater (Reception - Lower KS1)

1. Modelling Ocean currents (Upper KS2KS3)

2. Investigating changing densities in the Ocean (KS2 - KS3)

3. Modelling the water cycle (KS2)

4. Understanding light refraction in water (Upper KS2 - KS3)

5. Investigating Ocean acidification using pH indicator (Upper KS2 - KS3)

6. Observing the effects of Ocean acidification (shells) (Upper KS2 - KS3)

7. Observing the effects of Ocean acidification (exploding canisters) (Upper KS2 - KS3)

8. Investigating sea level rise (Upper KS2KS3)

Pages 4-12 Pages 14-24 Pages 25-34 Pages 35-42 Pages 43-49 Pages 50-57 Pages 59-64 Pages 65-78 Pages 79-84

Investigating the density of saltwater 1.

Target Age: Reception - Lower KS1

Delivery Time: 45 minutes

National Curriculum Links:

Observing closely, using simple equipment (Y1-2)

Performing simple tests (Y1-2)

Using their observations and ideas to suggest answers to questions (Y1-2)

Describe the simple physical properties of a variety of everyday materials (Y1)

Identify that most living things live in habitats to which they are suited (Y2)

Equipment per group:

Fresh egg

Container (with measurements in ml, e.g. a science beaker or jug) filled with tap water

Container of salt

Teaspoon

Stirring rod

Optional - Thermometers

Teacher Instructions:

1. Distribute a container of tap water to each group.

Divide the class into small groups, we recommend 56 students per group. Provide each student with a worksheet and a pencil to record their observations.

2. Have students measure the volume of water in millilitres (ml). As an optional extension, you can also ask them to measure the water temperature using a thermometer.

4. Provide each group with an egg. Ask them to place it in the water and observe what happens. Challenge the groups to explain scientifically why the egg sinks and why the water level rises.

Initiate a discussion and encourage students to share their predictions on what will happen to an egg when it's placed in the water.

5. Ask students to compare tap water with seawater. Guide them in discussing the differences.

6. Ask the students to predict what will happen to the egg if salt is added to the water. Challenge them to explain how the salt will behave when stirred into the water.

8. Give each group a container of table salt, a teaspoon, and a stirring rod. Instruct them to add one teaspoon of salt at a time, stirring until it dissolves. They should observe any changes in the egg. If no change occurs, continue adding salt, one spoonful at a time, until a change is noticed. Remind them to count how many spoonfuls it takes for the change to occur.

9. Once the eggs begin to float, ask students to explain why.

10. Compare results across groups. Discuss the reasons for any differences in the number of spoonfuls needed, such as varying salt mass, differences in egg freshness, or varying stirring techniques.

11. Discuss how to ensure a fair test, such as measuring the mass of salt each time or using identical eggs.

12. Conclude with a discussion on the importance of buoyancy for marine animals and how it affects their ability to float in the water column.

13. You can repeat this experiment by varying water temperature, measuring the temperature with the thermometer, and comparing how quickly the salt dissolves in warm water compared with cold water.

Teacher Context:

Density describes how tightly the mass of a material is packed into the space it occupies. A denser substance feels heavier for its size.

When the egg is placed in tap water, it sinks because the egg is denser (heavier) than the water. As the egg enters the water, it pushes out a volume of water equal to its own, to make space for itself. This process, known as displacement, explains why the water level rises in the container, even though no extra water is added— similar to how water levels rise when we step into a bathtub.

When salt is added to the water, the salt particles (solute) separate and spread evenly throughout the water (solvent), forming a solution and meaning the salt can no longer be seen. As the salt dissolves, it increases

the water’s density. Eventually, the saltwater becomes denser than the egg, causing the egg to float as it is pushed upward by the denser liquid.

The density of seawater varies across different parts of the Ocean due to several factors:

Salinity: The saltiness of seawater varies between 34-36 ppt (parts per thousand).

Temperature: Cold seawater is denser than warm seawater.

Depth: Denser seawater sinks below less dense seawater.

Pressure: Increased pressure can further raise seawater density at greater depths.

This activity demonstrates how the high salt content of seawater supports the large bodies of marine species, including giant squid and whales, allowing them to float in the Ocean without the need to evolve additional supporting structures. Salt water also exerts high pressure on deep sea species. These organisms have evolved to survive in these high-pressure habitats, without being compressed

Accompanying Student Worksheet:

Investigating the density of saltwater

1. When I add an egg to the water, I predict that _________________________________________________ _________________________________________________ _________________________________________________

What volume of water was in your beaker at the start? _________ Units _________

2. Draw what happened to the egg when you put it in the water.

4. When I added the egg to the water it _____________. This is because _____________________________________

5. When I add salt to the water, I predict that

6. Draw what happened to the egg when you added salt to the water.

7. When I added salt to the water ____________________ ____________________________________________________ This is because ______________________________________

Accompanying Student Worksheet: Investigating the density of saltwater ANSWERS

1. When I add an egg to the water, I predict that Students may have various predictions including the egg floating, sinking, peeling, cracking, exploding changing colour, or dissolving.

What volume of water was in your beaker at the start? _________ Units _________

2. Draw what happened to the egg when you put it in the water. 3.

4. When I added the egg to the water it sank. This is because the egg is heavier (more dense) than the water.

5. When I add salt to the water, I predict that Students may have various predictions including the egg, sinking, peeling, cracking, exploding, changing colour, or dissolving.

6. Draw what happened to the egg when you added salt to the water.

7. When I added salt to the water the egg started to float. This is because the salt made the water heavier (more dense) meaning it pushed the egg upwards causing it to float.

Make a splash this year!

Book your class in for an interactive curriculumlinked virtual tour of the UK’s National Aquarium!

Local or visiting the South West? Visit us in person or let us bring the Ocean to you with our exciting outreach sessions!

2. Modelling Ocean currents

Target Age: Upper KS2 - KS3

Delivery Time: 1 hour

This activity can be used alongside the ‘Investigating changing densities in the Ocean’ activity plan.

National Curriculum Links:

Identifying scientific evidence that has been used to support or refute ideas or arguments (Y5-6)

Similarities and differences, including density differences, between solids, liquids and gases (KS3)

The differences in arrangements, in motion and in closeness of particles explaining changes of state, shape and density (KS3)

Equipment per group:

2x Large, deep transparent container, e.g. a baking dish

Small, lidded container that won’t float in water and is suitable for hot liquids

Red and blue food colouring

Access to tap water

Ice cube tray

Teacher Instructions:

Before the experiment, prepare some ice cubes using water mixed with blue food colouring.

1. Fill both large, transparent containers with roomtemperature water.

2. In a small heat-safe container, add some red food colouring and warm water. Put the lid on afterwards.

3. Put the small, lidded container of warm red water in one of the large transparent containers of water, ensuring it is submerged.

Remove the lid of the container of red liquid and observe what happens. You should notice that the warm red liquid rises quickly to the surface because it is less dense.

Add the blue ice cubes to the surface of the water

in the other container and observe what happens. You should notice that the cold blue water from the ice cubes sinks to the bottom of the container because it is more dense.

Teacher Context:

Ocean water is not still, instead it is constantly moving due to the global Ocean conveyor belt. This motion is driven by Ocean currents at the surface due to wind and in the deep Ocean due to differences in density. The density of Ocean water is controlled by temperature and salinity. Cold water is more dense and sinks, whereas warm water is less dense and rises. This is called a convection current.

Water flowing into the polar regions gets colder, therefore increasing its density. Seawater has a lower freezing point than freshwater. When it is cold enough, the seawater freezes forming ice. This process pushes salt out of the water, making the surrounding water saltier and denser. This cold, dense water sinks deeper.

Warmer surface water, which is less dense moves into its place, forming a current called a convection current which drives global circulation.

In the activity, you should find that the cold, blue water from the ice cubes sinks, whereas the warm, red water from the container rises. This is because cold water is more dense, whereas warm water is less dense. This models a convection current, which drives Ocean currents.

Ocean currents affect the weather, climate and cycling of nutrients. The global Ocean conveyor belt is essential to maintaining Earth's climate stability, and any changes to this system (like the warming of the Oceans due to climate change) could have significant effects on global weather and ecosystems.

Accompanying Student Worksheet:

Modelling Ocean currents

Choose from the words below to complete the gaps in the sentence:

Heavier

Currents Differences Temperature

Water in the Ocean is constantly moving due to Ocean ___________.

Currents in the deep Ocean are caused by ________ in density.

Density is how tightly the mass of a material is packed into the space it occupies. A denser substance feels ________ for its size.

The density of Ocean water is controlled by the ________ and salinity. Salinity is a measure of how salty the water is.

Answer the following questions about the demonstration.

2. Describe what happened to the cold, blue water from the ice cubes when they were placed in the water?

3. Describe what happened to the warm, red water from the container when the lid was removed?

5. State whether cold water or warm water is more dense? _____________________

6. Add the following labels to the diagram of the convection current below:

Warm water is less dense, so it rises

7. Explain how convection currents form in the Ocean. Use the following keywords in your answer.

Freezes, Salt, Cold, Sinks, More Dense, Warm, Rises, Less Dense

8. Give a reason why Ocean currents are important.

Accompanying Student Worksheet:

Modelling Ocean currents ANSWERS

Choose from the words below to complete the gaps in the sentence:

Heavier

Currents Differences Temperature

Water in the Ocean is constantly moving due to Ocean currents.

Currents in the deep Ocean are caused by differences in density.

Density is how tightly the mass of a material is packed into the space it occupies. A denser substance feels heavier for its size. The density of Ocean water is controlled by the temperature and salinity. Salinity is a measure of how salty the water is.

Answer the following questions about the demonstration.

2. Describe what happened to the cold, blue water from the ice cubes when they were placed in the water? When the blue ice cubes were placed in the water, the cold blue water sank to the bottom of the container.

3. Describe what happened to the warm, red water from the container when the lid was removed? When the lid was removed from the container, the warm, red water rose to the surface.

5. State whether cold water or warm water is more dense? Cold water is more dense and warm water is less dense.

6. Add the following labels to the diagram of the convection current below: Warm water is less dense, so it rises

cools, becomes less dense and sinks

Water cools, becomes more dense and sinks

Warm water is less dense, so it rises

7. Explain how convection currents form in the Ocean. Use the following keywords in your answer.

Freezes, Salt, Cold, Sinks, More Dense, Warm, Rises, Less Dense

Cold water from the poles freezes into ice. Salt from the seawater is pushed out of the ice into the surrounding water. The cold, salty water sinks down to the bottom of the Ocean because it is more dense. Warm surface water, which is less dense, rises and moves in to take its place. This process forms the convection current.

8. Give a reason why Ocean currents are important. Weather, climate, cycling of nutrients, maintaining Earth's climate stability

DIVE INTO LEARNING SPRING 2025

6th March

World Book Day

11th February Women & Girls in Science

10th-14th March

British Science Week

3rd-7th March

Careers Week

3. Investigating changing densities in the Ocean

Target Age: KS2 - KS3

Delivery Time: 45 minutes

This activity can be used alongside the ‘Modelling Currents’ activity plan.

National Curriculum Links:

Making systematic and careful observations (Y3-4)

Using results to draw simple conclusions (Y3-4)

Identify how animals and plants are adapted to suit their environment in different ways and that adaptation may lead to evolution (Y6)

Similarities and differences, including density differences, between solids, liquids and gases (KS3) The differences in arrangements, in motion and in closeness of particles explaining changes of state, shape and density (KS3)

Equipment per group:

A transparent, narrow, cylindrical container, for example a tall, narrow jar or drinking glass

x2 Pipettes

Honey (in a squeezy bottle is easiest to pour)

Washing up liquid

Vegetable Oil

Teacher Instructions:

Carefully pour the honey (or most dense liquid) into the bottom of the container, aiming to avoid touching the side of the glass. Create a layer approximately 5cm high.

Carefully add the washing up liquid on top of the honey. To prevent mixing, use a pipette to slowly layer the liquid, forming a layer about 3cm high.

2. Finally add the vegetable oil using a clean pipette. Pour a layer that is about 2cm high.

3. You can repeat this experiment using different liquids of various densities.

Teacher Context:

Density describes how tightly the mass of a material is packed into the space it occupies. A denser substance feels heavier for its size.

Honey settles at the bottom of the container because it has the highest density. The washing-up liquid, with a slightly lower density, forms the middle layer, while the vegetable oil remains at the top as it has the lowest density.

This simple activity can be a helpful way to illustrate how density changes in the Ocean. Seawater density varies across different regions due to several factors:

Salinity: The saltiness of seawater typically ranges from 34 to 36 parts per thousand (ppt).

Temperature: Colder seawater is denser than warmer seawater.

Depth: Denser water sinks, while less dense water rises, leading to layering in the Ocean.

Pressure: At greater depths, increased pressure can further increase seawater density.

The Ocean can be divided into 3 different layers due to differences in density: the mixed surface layer, pycnocline layer and deep layer.

The mixed surface layer at the top is warmer and less dense. It is called the mixed layer because the wind stirs the surface waters, creating a well-mixed layer of uniform density. In the model, the mixed layer is represented by the vegetable oil.

The pycnocline layer separates the mixed surface layer and the deep layer. Here, water density increases rapidly with depth because of changes in temperature and/or salinity. In the model, the pycnocline layer is represented by the washing up liquid.

The bottom layer of water is called the deep layer, which is cold and the most dense. This layer accounts for most of the Ocean's mass. Within the deep layer, density increases gradually with depth and water moves slowly. In the model, the deep layer is represented by the honey.

This activity can be used to discuss how marine species are adapted to survive at different depths in the Ocean. Many fish have an organ called a swim bladder, which they use to control buoyancy and change their density, allowing them to swim at different depths in the Ocean. However, deep sea species have adapted to survive by having dense bony bodies, without a swim bladder.

www.mammothmemory.net

Complete the definition for density. Density is

After completing the activity, add the following labels to the diagram below: 2.

3. Which liquid was the most dense? __________________

4. Which liquid was the least dense? __________________ 5. Choose from the words below to complete the gaps in the sentence:

Density Cold Warm Mixed Deep Pycnocline

__________ water is more dense and sinks, whereas __________ water is less dense and rises. The Ocean can be divided into 3 layers due to differences in __________.

The top layer is called the ___________ surface layer because the wind stirs the water at the surface.

The middle layer is called the ___________. As you go deeper in this layer, the density increases rapidly.

The bottom layer is called the _________ layer. Here, density increases gradually with depth and the water moves slowly.

6. In the activity, honey, vegetable oil and washing up liquid were used to represent the different layer of the Ocean. In question 2, write the following labels next to the correct liquid used in the model:

Accompanying Student Worksheet: Investigating changing densities in the Ocean ANSWERS

Complete the definition for density. Density is how tightly the mass of a material is packed into the space it occupies. A denser substance feels heavier for its size.

After completing the activity, add the following labels to the diagram below: 2.

Vegetable Oil (Mixed surface layer)

Washing Up Liquid (Pycnocline Layer)

Honey (Deep Layer)

3. Which liquid was the most dense? Honey

4. Which liquid was the least dense? Vegetable Oil

5. Choose from the words below to complete the gaps in the sentence:

Density Cold Warm Mixed Deep Pycnocline

Cold water is more dense and sinks, whereas warm water is less dense and rises.

The Ocean can be divided into 3 layers due to differences in density.

The top layer is called the mixed surface layer because the wind stirs the water at the surface.

The middle layer is called the pycnocline. As you go deeper in this layer, the density increases rapidly.

The bottom layer is called the deep layer. Here, density increases gradually with depth and the water moves slowly.

SPRING EVENTS

Women & Girls in Science 11th February

Join a free virtual panel featuring inspiring women in marine science.

Explore different careers within marine science to inspire your students.

Learn about each guest’s career journey and educational pathway.

Send in questions for the panel in advance, or ask live on the day.

World Book Day 6th March

Add magic to your World Book Day with a live virtual session from the NMA!

Join one of our resident mermaids live from her enchanting mermaid cave.

Enjoy a unique Ocean-themed story covering topics linked to the EYFS Statutory Framework and Key Stage 1 curriculum.

Use our free downloadable resources to enhance the learning and magic of the day.

Careers Week

Discover diverse careers here at the Ocean Conservation Trust.

3rd-7th March

Choose from one of our three bespoke tours which focus on either Marine Biology, Engineering or an overview of some of the exciting jobs here at the NMA.

Go behind the scenes to meet the team and explore careers, subjects, and education options.

Add a hands-on workshop to develop skills and knowledge from your tour.

British Science Week 10th-14th March

Using this year’s theme, “Adapt and Change,” we will explore some of the amazing changes that occur on our planet and within our Ocean, and we will also launch our brand-new show!

Schools visiting the NMA for a fully interactive day during British Science Week get FREE access to the show at day's end.

Can’t visit? We'll bring the show to you for just £100 per school!

Download FREE activity plans with classroom-friendly experiments on physical and chemical changes in the Ocean.

For more information scan here or contact us on learning@oceanconservationtrust.org

4. Modelling the water cycle

Target Age: KS2

Delivery Time: 1 hour

National Curriculum Links:

Making systematic and careful observations (Y3-4)

Identify the part played by evaporation and condensation in the water cycle and associate the rate of evaporation with temperature (Y4)

Equipment per group:

Large plastic mixing bowl

Clingfilm

A mug

String or tape

Water

A marble or something of a similar mass

Teacher Instructions:

Place the mug inside the bowl.

Add water to the bowl around the mug, so that it comes up to 2/3 the mug’s height but doesn’t fill it.

3. Draw on the edge of the bowl to mark the start height of the water.

4. Cover the bowl tightly with clingfilm and fasten it in place with the string or tape to create a sealed environment to trap water vapour.

5. Place the marble on top of the clingfilm in the middle to weigh down the centre.

6. Leave the bowl in a warm place, for example by a sunny window or next to a radiator, for a week or two. Check the bowl at regular intervals. Each time you check, mark the new water height on the edge of the bowl. After a few days, you should notice some condensation on the clingfilm and some water droplets inside the mug, demonstrating how water vapor condenses when cooled.

7. Discuss as a class how the different parts of the water cycle are being represented in the model.

Teacher Context:

All the water on Earth is constantly moving and is cycled through the water cycle.

1. Evaporation: Water bodies, such as the sea or lakes, are warmed by the sun. The heat causes the liquid water to evaporate into water vapour, a gas, which rises into the atmosphere.

2. Condensation: As the water vapour rises higher into the atmosphere, it cools down and condenses back into tiny droplets, forming clouds.

3. Precipitation: Eventually, the clouds get too heavy and liquid water falls as precipitation (rain, snow, hail or sleet) back to the Earth’s surface.

4. Collection: After precipitation, water travels over the land and collects in rivers, lakes, or underground reservoirs, which return it back to the sea. This completes the cycle, allowing the process to start again.

4. Collection

3. Precipitation

2. Condensation

Here's how the different parts of the model represent each stage of the water cycle:

The water in the bowl represents bodies of water like the Oceans from which water evaporates.

The warm environment (e.g., by a sunny window or radiator) represents the sun, which heats up the water and causes evaporation.

The clingfilm cover acts like the atmosphere where water vapour rises and cools down. As the vapour cools, it condenses on the clingfilm forming liquid droplets, similar to how clouds form in the atmosphere.

The mug represents bodies of water like lakes or rivers, where water collects after precipitation.

Even though the Earth is covered by vast amounts of water, most of it is either saltwater or trapped in glaciers, ice caps or underground. Only about 0.3% of the fresh water on Earth is found in accessible forms such as lakes, rivers, and swamps. Because fresh water is such a scarce resource, it’s important to conserve it and use it responsibly.

Accompanying Student Worksheet: Modelling the water cycle

1. Evaporation

Add the following labels to the diagram of the water cycle:

Condensation

Precipitation

Collection

2. Write a description for each stage of the water cycle:

Evaporation: _________________________________________________ _________________________________________________

Condensation: _________________________________________________ _________________________________________________

Precipitation:

Collection:

3. State 5 different ways you use water:

4. Suggest 5 ways you could use less water:

Accompanying Student Worksheet:

Modelling the water cycle ANSWERS

Add the following labels to the diagram of the water cycle:

Condensation

Precipitation

Collection

Precipitation

Condensation

Evaporation

Collection

2. Write a description for each stage of the water cycle: Evaporation: Water bodies are warmed by the sun. The heat causes the liquid water to evaporate into water vapour, a gas.

Condensation: As the water vapour rises higher into the atmosphere, it cools down and condenses back into tiny droplets, forming clouds.

Precipitation: Eventually, the clouds get too heavy and liquid water falls as precipitation (rain, snow, hail or sleet) back to the Earth’s surface.

Collection: After precipitation, water travels over the land and collects in rivers, lakes, or underground reservoirs, which return it back to the sea.

3. State 5 different ways you use water: Drinking, baths or showers, brushing our teeth, cooking, flushing the toilet, washing our hands, washing the car, watering garden plants, washing clothes

4. Suggest 5 ways you could use less water: Reduce how often you have a bath or take short showers instead, turn the tap off when brushing your teeth or scrubbing your hands, collecting rain water or use bath water to water garden plants, re-wear clothes or re-use towels a few times before washing them, reduce food waste

5. Understanding light refraction in water

Target Age: Upper KS2 - KS3

Delivery Time: 1 hour

National Curriculum Links:

Recognise that light appears to travel in straight lines (Y6)

Use of ray model to explain imaging in mirrors, the pinhole camera, the refraction of light and action of convex lens in focusing (qualitative); the human eye (KS3)

Equipment per group:

A narrow glass half filled with water (you may need to experiment beforehand with various glasses, as the shape of the glass can affect the result)

Marker pen

Piece of A4 paper

Pencil

Teacher Instructions:

Experiment 1:

Place the pencil in the water and rest it against the rim of the glass.

Observe the pencil from various angles. When looking at the pencil in line with the water’s surface, it should look like the pencil is broken. 2.

Remove the pencil to show that it has not snapped!

Experiment 2:

On a piece of paper, draw a small arrow using a marker pen. 1. Fill the glass with water. 2. Put the piece of paper behind the glass of water. The direction of the arrow should flip.

3. You can experiment with different drawings. 4.

Teacher Context:

The density of a material affects the speed at which light will be transmitted through it. Light refraction is the bending of light and this is different to reflection. When light rays pass from one medium to another, they either speed up or slow down. This causes the ray of light to change direction.

Below is a light refraction diagram. The normal is an imaginary line, at a right angle to the boundary between the two substances.

If light moves from a less dense medium (e.g. air) to a more dense medium (e.g. glass or water), it slows down, causing the ray to bend towards the normal. If light moves from a more dense medium (e.g. glass or water) to a less dense medium (e.g. air), it speeds up, causing it to bend away from the normal.

The light refraction activities in this activity pack demonstrate how light rays change speed and direction as they pass from air to glass to water, distorting the image of the pencil or the arrows.

Apparent position

Actual position

Archer fish, which live in the rivers and seas of SouthEast Asia, target fish on branches above the water. They knock down their prey using a jet of water. However, water and air have different densities, meaning the prey

is not actually where it appears to be unless the fish is looking at it from directly below. The Archer fish have adapted to learn how to account for light refraction when aiming at prey and can calculate where they expect the prey will land in the water. Google search ‘archer fish catch prey’ to find a video of this in action!

Apparent position

Actual position

Many birds, including herons, have also learned how to account for light refraction when hunting for fish beneath the water’s surface. By understanding that the fish is located in a different position to what they see, they can successfully aim their attack.

Accompanying Student Worksheet:

Modelling the water cycle

State what refraction of light is.

Describe how light refraction happens.

2. If light passes from a less dense substance to a denser substance, does it speed up or slow down?

3. If light passes from a denser substance to a less dense substance, does it speed up or slow down?

Explain why in the activities, the pencil appeared broken and the arrow changed direction.

Give an example of a species that has adapted to cope with the refraction of light in order to catch prey.

Accompanying Student Worksheet:

Modelling the water cycle ANSWERS

State what refraction of light is. Light refraction is the bending of light.

Describe how light refraction happens. When light rays pass from one medium to another, they either speed up or slow down. This causes the ray of light to change direction.

3. If light passes from a denser substance to a less dense substance, does it speed up or slow down? Speeds up

If light passes from a less dense substance to a denser substance, does it speed up or slow down? Slows down

Explain why in the activities, the pencil appeared broken and the arrow changed direction. Light rays change speed and direction as they pass from air to glass to water, because of the density of the medium. This distorts the image of the pencil or the arrows.

Give an example of a species that has adapted to cope with the refraction of light in order to catch prey. The Archer fish have adapted to learn how to account for light refraction when aiming at prey and can calculate where they expect the prey will land in the water.

DIVE INTO LEARNING SPRING 2025

6th March

World Book Day

11th February Women & Girls in Science

10th-14th March

British Science Week

3rd-7th March

Careers Week

6. Investigating Ocean acidification using pH indicator

Target Age: Upper KS2 - KS3

Delivery Time: 1 hour

This activity can be used alongside the ‘Observing the effects of Ocean acidification (shells)’ and ‘Observing the effects of Ocean acidification (exploding canisters)’ activity plans.

National Curriculum Links:

Recording data and results of increasing complexity using scientific diagrams and labels, classification keys, tables, scatter graphs, bar and line graphs (Y56)

Planning different types of scientific enquiries to answer questions (Y5-6)

Make predictions using scientific knowledge and understanding (KS3)

Defining acids and alkalis in terms of neutralisation reactions (KS3)

The pH scale for measuring acidity/alkalinity; and indicators (KS3)

Equipment per group:

A few small pieces of red cabbage

Mug

Kettle (to share among group and to be used by an adult)

Container for the red cabbage indicator

Eye protection for all students

Lab coats for all students

Gloves for all students

Test tube rack (if using test tubes)

Dropper pipette

Test tubes or small containers labelled and half filled with a variety of liquids, e.g. Baking soda (dissolved in water), tap water, lemon juice, orange juice, antacid tablets (dissolved in water) e.g. Rennie, mouth wash, milk, toothpaste (mixed with a little water), white vinegar

Teacher Instructions:

Prior to the lesson

1. Leave for 10 minutes.

Add a few small pieces of red cabbage to a mug and cover with freshly boiled water.

2. The liquid is your cabbage solution to use as an indicator. Leave to completely cool before using.

During the lesson

1. Ensure students are wearing eye protection, gloves and lab coats for safety.

Complete the predictions column of the results table of the worksheet.

Using a dropper pipette, add a few drops of the cabbage solution to each test tube. Observe and record the colour of the cabbage solution in each test tube.

Refer to the cabbage indicator pH scale to identify whether the liquids are acidic, alkaline, or neutral based on the colour changes. Record the results in the results table.

Teacher Context:

The pH scale is a measure of how acidic or alkaline a substance is, ranging from 0 to 14. Acids, such as stomach acid, have a pH between 0 and 6 — the closer to 0, the stronger the acid. Neutral substances, like pure water, have a pH of 7. Alkalis, such as bleach, have a pH between 8 and 14 — the closer to 14, the stronger the alkali. The ocean has a pH of 8.1, and marine life has adapted to thrive in these slightly alkaline conditions.

www.science-sparks.com

To determine the pH of a substance, you can use an indicator, which changes colour depending on the substance’s pH. While Universal Indicator is commonly used in science classes, you can also create a safe and effective indicator from red cabbage at home.

Accompanying Student Worksheet:

Investigating Ocean acidification

using pH indicator

Liquid Prediction: Acid, Alkali or Neutral? Colour with Cabbage Indicator pH (0-14)

Test Result: Acid, Alkali or Neutral?

Accompanying Student Worksheet:

Investigating Ocean acidification using pH indicator ANSWERS

Please note your results may vary slightly depending on product brands.

Put the liquids that you tested in order of pH, from the strongest acid to the strongest alkali: Lemon Juice

DIVE INTO LEARNING AT THE

7. Observing the effects of Ocean acidification (shells)

Target Age: Upper KS2 - KS3

Delivery Time: 1 hour

This activity can be used alongside the ‘Investigating Ocean acidification using pH indicator’ and ‘Observing the effects of Ocean acidification (exploding canisters)’ activity plan.

National Curriculum Links:

Planning different types of scientific enquiries to answer questions (Y5-6)

Make predictions using scientific knowledge and understanding (KS3)

Defining acids and alkalis in terms of neutralisation reactions (KS3)

The pH scale for measuring acidity/alkalinity; and indicators (KS3)

The production of carbon dioxide by human activity and the impact on climate (KS3)

Equipment per group:

White vinegar

Seawater (approximately 1 ½ teaspoons of salt per 250ml water)

2x Clear glass or plastic jars per group

2x Seashells per group, e.g. limpet shell

Teacher Instructions:

Place a seashell in each container.

1. Fill one container with seawater, ensuring the shell is fully submerged, and label it "Seawater." This will serve as the control.

3. Over the next week, have students check the shells daily and record any observed changes on their results worksheet.

Fill the other container with vinegar, ensuring the shell is fully submerged, and label it "Vinegar."

Teacher Context:

When fossil fuels (such as coal, crude oil, or natural gas) are burned, carbon dioxide (CO2) is produced. This occurs in power stations generating electricity, cars burning petrol or diesel, and during the production of materials like plastic. Carbon dioxide is a greenhouse

gas, meaning that when it accumulates in the Earth's atmosphere, it contributes to global warming and climate change. However, it’s worth noting that carbon dioxide exhaled by animals does not significantly contribute to climate change.

Scientists estimate that between 25-27% of atmospheric carbon dioxide (released from burning fossil fuels) is absorbed by the ocean. This absorption leads to a change in the ocean's chemical composition, causing it to become more acidic. This process, called ocean acidification, is a key impact of climate change. A group of animals known as molluscs, such as crabs and clams, typically develop shells made of calcium carbonate as part of their exoskeleton. However, increased ocean acidity weakens these calcium carbonate shells, posing a threat to these marine creatures.

Vinegar is an acid and therefore can be used to model an acidic ocean. While the ocean is not expected to become as acidic as vinegar under current climate change projections, this activity demonstrates an extreme outcome to highlight the extreme effects of increased acidity.

Accompanying Student Worksheet:

Observing the effects of Ocean acidification (shells)

Predict what will happen to the shell after leaving it in vinegar: ______________________________________

1. After a few days, compare the shell in seawater and vinegar. Draw each shell below: 2.

Drawing of the shell at the start of the experiment

Drawing of the shell after ___ days

3. Describe what happened to the shell in the vinegar.

4. Explain why this happened to the shell in the vinegar.

5. Suggest why this effect might be a problem for marine animals with a calcium carbonate shell.

Accompanying Student Worksheet:

Observing the effects of Ocean acidification (shells) ANSWERS

Predict what will happen to the shell after leaving it in vinegar: Students own prediction.

1. After a few days, compare the shell in seawater and vinegar. Draw each shell below: 2.

Please note your results may vary slightly depending on the type and thickness of shells used.

3. Describe what happened to the shell in the vinegar. Bubbles of carbon dioxide gas were produced and over time, the shell became thinner, weaker and cracked.

4. Explain why this happened to the shell in the vinegar. The shell in the vinegar was exposed to acidic conditions. The acid weakened the shell, breaking down its structure. The gas produced is carbon dioxide.

5. Suggest why this effect might be a problem for marine animals with a calcium carbonate shell. Animals need shells or exoskeletons for protection. If their shells or exoskeletons are weakened or damaged because of ocean acidification, they will be less able to protect themselves from predators. They will also need to use more energy to repair their shell/exoskeleton, at the expense of using this energy to find food or reproduce.

Make a splash this year!

Book your class in for an interactive curriculumlinked virtual tour of the UK’s National Aquarium!

Local or visiting the South West? Visit us in person or let us bring the Ocean to you with our exciting outreach sessions!

8. Observing the effects of Ocean acidification (exploding canisters)

Target Age: Upper KS2 - KS3

Delivery Time: 2 hours

This activity can be used alongside the ‘Investigating Ocean acidification using pH indicator’ and ‘Observe the effects of Ocean acidification (shells)’ activity plans.

National Curriculum Links:

Planning different types of scientific enquiries to answer questions, including recognising and controlling variables where necessary (Y5-6)

Taking measurements, using a range of scientific equipment, with increasing accuracy and precision, taking repeat readings when appropriate (Y5-6)

Recording data and results of increasing complexity using scientific diagrams and labels, classification keys, tables, scatter graphs, bar and line graphs (Y56)

The pH scale for measuring acidity/alkalinity; and indicators (KS3)

The production of carbon dioxide by human activity and the impact on climate (KS3)

Select, plan and carry out the most appropriate types of scientific enquiries to test predictions, including identifying independent, dependent and control variables (KS3)

Present observations and data using appropriate methods, including tables and graphs (KS3)

Interpret observations and data, including identifying patterns and using observations, measurements and data to draw conclusions (KS3)

Equipment per group:

Film cannisters (generally, used film cannisters work better than brand new cannisters, as the seal on brand new cannisters can be too tight)

Alka-Seltzer tablets x45 (for 5 groups of 6 students)

675ml White vinegar (for 5 groups of 6 students)

Pipette or another vessel to measure 10ml

Eye protection for all students

Stop watches

Pestle and Mortar

Small containers, e.g. weighing boats, to decant ground tablets into

Teacher Instructions:

1. Divide the students into 5 groups and provide each group with a film canister.

Conduct this activity in a spacious area, preferably outdoors or in a room with high ceilings. Ensure all students are wearing eye protection.

2. Have students use a pipette to measure 15ml of vinegar into the film canister.

3. Instruct students to remove the lid from the film canister and hold the lid in one hand and an AlkaSeltzer tablet in the other.

4. The next step needs to be carried out quickly. Count down and have students drop the AlkaSeltzer tablet into the vinegar, quickly secure the lid on the canister, move back 2 metres, and wait for the reaction.

As soon as the lid is sealed, start the stopwatch and time how long it takes for the canister to explode (Note - this may happen very quickly!).

6. If the vinegar leaks or the canister does not explode, students should remain at a safe distance and alert a teacher to inspect the canister with care.

After the reaction, observe the remains of the Alka-Seltzer tablet.

9. Record the time it took for the cannister to explode in the table.

10. Rinse the film canister with water and repeat steps 3-9 twice more. Calculate a mean using the 3 results.

11. Then repeat steps 3-10 using a tablet broken into smaller pieces, and a tablet crushed into a powder.

Teacher Context:

The exploding film canister experiment demonstrates a simple chemical reaction and the concept of gas pressure. When the Alka-Seltzer tablet dissolves in vinegar, it reacts to form carbon dioxide gas. The carbon dioxide gas rapidly builds up inside the sealed film canister, causing the pressure to increase. Once the pressure inside the canister is too high, the lid of the canister is forced off, causing an “explosion”.

The experiment can also act as a simple model for ocean acidification, with the vinegar representing an acidic ocean and the Alka-Seltzer tablet acting as an animal with a calcium carbonate skeleton, such as coral or a lobster. After the explosion, observe the remains of the Alka-Seltzer tablet. You’ll notice it has begun to

dissolve and break apart. While ocean acidification doesn’t cause animals to explode, this experiment highlights the harmful impacts an acidic ocean can have on marine animals with a delicate exoskeletons.

Rate of reaction describes the time it takes for a chemical reaction to occur. The rate of a chemical reaction can be increased by increasing the surface area of the reactants, in this case the Alka-Seltzer tablet. This can be achieved by breaking the tablet into small pieces, or by grinding it into a powder.

To summarise:

Large pieces = small surface area = slow reaction rate

Small pieces (powder) = large surface area = fast reaction rate

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A larger surface area means more particles of the reactant are exposed to the other reactant. This increases the chance that particles will collide, leading to more successful collisions between reactants and therefore a faster rate of reaction.

Scientific investigations have an aim, hypothesis (scientific prediction) and variables:

Independent variable - what is being changed

Dependent variable - what is being measured

Control variables - what is being kept the same to ensure a fair test

Accompanying Student Worksheet:

Observing the effects of Ocean acidification (exploding canisters)

Before completing the investigation, complete the hypothesis and variables below: 1.

Aim: To investigate how surface area affects the rate of reaction.

State your hypothesis:

State the independent variable:

State the dependent variable:

State the control variables:

2. During the investigation, complete the table below with the results:

for the explosion (s)

Number of pieces the tablet has been broken into

Whole Tablet

Tablet broken into smaller pieces

Tablet broken into a powder

Hint - To calculate the mean, add up the 3 values for each experiment and divide the total by 3.

3. Complete the y-axis title and values. Plot your results (as a bar chart) on the axes below using your mean values.

Y axis title:

Tablet broken into smaller pieces

Tablet broken into a powder

Number of pieces the tablet has been broken into Whole tablet

4. State whether the reaction happened fastest when the tablet was whole, broken into smaller pieces, or broken into a powder.

5. Explain why this happened:

6. Explain how this experiment acts as a model for ocean acidification.

Accompanying Student Worksheet:

Observing the effects of Ocean acidification (exploding canisters)

ANSWERS

Before completing the investigation, complete the hypothesis and variables below: 1.

Aim: To investigate how surface area affects the rate of reaction.

State your hypothesis: I predict that the tablet as a whole/ broken into smaller pieces/ broken into a powder will react with the vinegar the fastest.

State the independent variable: The independent variable is the surface area of the tablet, so whether it had a small surface area (the whole tablet) or a large surface area (the powder).

State the dependent variable: The dependent variable is the time it takes in seconds for the cannister to explode.

State the control variables: The control variables include the volume of vinegar, the size of the cannister, the mass of the Alka-Seltzer tablet, the brand of vinegar and Alka-Seltzer tablet, and the amount you shake the mixture.

2. During the investigation, complete the table below with the results: Example results - Please note that your results may vary depending on the condition of the film cannister.

Number of pieces the tablet has been broken into

for the explosion (s)

3. Complete the y-axis. Plot your results (as a bar chart) on the axes below using your mean values.

axis title: Time taken for the explosion (s) Number of pieces the

4. State whether the reaction happened fastest when the tablet was whole, broken into smaller pieces, or broken into a powder. The tablet broken into a powder had the fastest rate of reaction.

5. Explain why this happened:

This was because the powder has a larger surface area than the larger pieces. Therefore, more of the AlkaSeltzer tablet particles will collide with the vinegar, leading to more successful collisions between reactants. This leads to a faster rate of reaction, producing carbon dioxide at a faster rate, leading to a faster explosion!

6. Explain how this experiment acts as a model for ocean acidification.

The vinegar models an acidic ocean and the Alka-Seltzer tablet models an animal with a calcium carbonate exoskeleton, such as a coral. The vinegar reacts with the tablet to weaken its structure and cause it to crumble.

The ocean isn’t as acidic as vinegar, but higher acidity levels will weaken animal’s calcium carbonate exoskeletons.

SPRING EVENTS

Women & Girls in Science 11th February

Join a free virtual panel featuring inspiring women in marine science.

Explore different careers within marine science to inspire your students.

Learn about each guest’s career journey and educational pathway.

Send in questions for the panel in advance, or ask live on the day.

World Book Day 6th March

Add magic to your World Book Day with a live virtual session from the NMA!

Join one of our resident mermaids live from her enchanting mermaid cave.

Enjoy a unique Ocean-themed story covering topics linked to the EYFS Statutory Framework and Key Stage 1 curriculum.

Use our free downloadable resources to enhance the learning and magic of the day.

Careers Week

Discover diverse careers here at the Ocean Conservation Trust.

3rd-7th March

Choose from one of our three bespoke tours which focus on either Marine Biology, Engineering or an overview of some of the exciting jobs here at the NMA.

Go behind the scenes to meet the team and explore careers, subjects, and education options.

Add a hands-on workshop to develop skills and knowledge from your tour.

British Science Week 10th-14th March

Using this year’s theme, “Adapt and Change,” we will explore some of the amazing changes that occur on our planet and within our Ocean, and we will also launch our brand-new show!

Schools visiting the NMA for a fully interactive day during British Science Week get FREE access to the show at day's end.

Can’t visit? We'll bring the show to you for just £100 per school!

Download FREE activity plans with classroom-friendly experiments on physical and chemical changes in the Ocean.

For more information scan here or contact us on learning@oceanconservationtrust.org

9. Investigating sea level rise

Target Age: KS2 - KS3

Delivery Time: 1 hour

National Curriculum Links:

Identify the part played by evaporation and condensation in the water cycle and associate the rate of evaporation with temperature (Y4)

Conservation of material and of mass, and reversibility, in melting, freezing, evaporation, sublimation, condensation, dissolving (KS3)

The production of carbon dioxide by human activity and the impact on climate (KS3)

Equipment per group:

2x Large plastic containers

2x Blocks of wood or smaller plastic containers to model the land

A ruler

A marker pen

10x Ice cubes (food colouring optional)

Access to water

Blue tac

Teacher Instructions:

Use blue tac to secure the wooden blocks or smaller plastic containers inside the large plastic containers. These will model the land.

1. Use the ruler and marker pen to mark a line on each of the large plastic containers at an equal height.

2. Add 5 ice cubes to each container. Ice cubes on the ‘land’ will model land ice (label this container land ice), and the ice cubes at the bottom of the large container will model sea ice (label this container land ice).

3. Fill each container with water up to the fill line.

4. Leave the ice cubes until they have melted.

5. Compare the height of the water to that of the original line.

Land Ice Sea Ice

Teacher Context:

Sea ice forms when water at the surface gets cold enough to freeze, whereas land ice forms due to the compaction and recrystallisation of snow and other precipitation.

Both land and sea ice melt due to warming global temperatures. When land ice melts, it adds stored water to water bodies such as the ocean, thus resulting in sea level rise.

Alternatively, when sea ice melts, it doesn’t cause the sea level to rise by a lot. Sea ice that floats on the sea displaces its own weight in the water. Floating ice is made of fresh water, which is less dense than salt water. When the fresh water ice melts, it takes up more volume than the sea water it displaced when it was ice. This raises the sea level very slightly, but not as much as land ice melt.

In the investigation, you should find that the ice melt in the land ice model raises the water level above the original line. Whereas the ice melt in the sea ice model doesn’t raise the water level, because the ice displaced its own weight in the water.

Sea level rise is a consequence of climate change, and sea levels are estimated to have risen by approximately 20-23 cm since 1880.

Currently, 2.15 billion people live in the near-coastal zone, which is defined as all land within 100 km from the coast at an elevation of up to 100 m. These areas are highly populated due to opportunities including fishing, trade, tourism, natural beauty, recreation and milder climates.

However, flooding due to sea level rise can cause many issues for these coastal communities, including: damage to coastal habitats, damage to farming land and infrastructure, impacts on peoples’ livelihoods and tourism infrastructure, and contamination of freshwater supplies. As a result, people may need to migrate or move to higher ground.

Climate Central have an interactive map on their website which shows areas threatened by future sea level rise and coastal flooding. To find this resource, Google search ‘climate central coastal risk screening tool’.

Accompanying Student Worksheet:

Investigating sea level rise

1. State the cause of sea ice and land ice melt.

Explain the difference between sea ice and land ice formation.

2. Explain how melting land ice causes sea levels to rise significantly.

Explain how when sea ice melts, it does not cause significant sea level rise.

State some of the consequences of sea level rise: 5.

Accompanying Student Worksheet:

Investigating sea level rise

ANSWERS

Explain the difference between sea ice and land ice formation. Sea ice forms when water at the surface gets cold enough to freeze, whereas land ice forms due to the compaction and recrystallisation of snow and other precipitation.

State the cause of sea ice and land ice melt. Temperature increase due to climate change.

Explain how melting land ice causes sea levels to rise significantly. When land ice melts, it adds stored water to water bodies such as the ocean, thus resulting in sea level rise.

Explain how when sea ice melts, it does not cause significant sea level rise. Sea ice that floats on the sea displaces its own weight in the water. When the sea ice melts, the volume of liquid water that is added to the sea, is equal to that which was stored in the frozen ice. This means sea ice melt doesn’t raise the sea level, because the ice displaced its own weight in the water.

State some of the consequences of sea level rise: damage to coastal habitats, farming land and infrastructure, impacts on peoples’ livelihoods and tourism infrastructure, contamination of freshwater

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