How we are formed

My objectives are: a) What scientific object did Leeuwenhoek use in his discovery? b) Where did he find the protozoa and bacteria? c) What kinds of human cells did he see with his microscopes? d) What did people use to think about where animals came from?

• To learn about the characteristics of living organisms.

• To know the three vital functions.

• To study cells.

• To understand what tissues, organs and body systems are.

Watch and learn!

• What do you know about the body systems?

Learning about cells is very interesting!

A long time ago, people didn’t know about microorganisms because they are too small to be seen with the naked eye.

In the 17th century, a Dutchman called Anton van Leeuwenhoek made a huge discovery. He developed microscopes that could magnify objects 300 times. This was much more than the microscopes that already existed.

One day, while he was observing water from a pond in his microscope, he discovered tiny living organisms. He called them ‘animalcules’. Today, however, we know that they were protozoa and bacteria.

It was the first time in history that somebody saw unicellular organisms. Thanks to van Leeuwenhoek’s curiosity, he was also able to observe red blood cells and spermatozoa. Until then, people used to think that animals appeared from nothing.

This caused a great shock and opened a new path for science in understanding how living organisms work.

2 Answer the following questions in your notebook.

Used to People used to think…

3 Find out what other important discoveries scientists made using microscopes. Write a list and share it with a classmate.

Let’s explore hoW we are formed

We are living organisms We are formed of cells

Cells form tissues

Tissues form organs

Organs form systems