Monstrous Problems Hotel De Tenebris 3

S U O R T S N O M S M E L B O R P T E L U M A E H ON T O M L L U F E H T F O

S U O R T S MON EMS L B O PR T MULE A E ON TH L MO L U F E OF TH

Please sign the guest book!

My name is ______________________ I like ______________________ I don’t like ______________________

1

Open the book to the middle: remove the sheet with the stickers and the one with the hotel map and the list of suspects.

2 Read the first part of the story, do the exercises

and collect the clues. Then check pages 2 and 3 to see which suspects have an item matching the one found, and stick the sticker on the suspect grid. The only suspect who has all the clue items will be the culprit!

3 Keep reading the story to find out where the culprit is hiding: make your way through the hotel, following the clues on the pages and checking the map: the culprit is hiding in the final room with the precious stolen goods!

ARE YOU READY TO ENTER THE HOTEL DE TENEBRIS?

EVERYTHING IS READY AT THE HOTEL DE TENEBRIS FOR THE DARK GRAND GALA. THE LIGHTING IS SUBDUED, THE TABLES ARE SET… AND YET, LURKING IN THE SHADOWS, SOMEONE SEEMS A LITTLE NERVOUS. GONE! IT’S REALLY GONE! I’VE LOOKED EVERYWHERE, BUT THERE’S NO SIGN OF MY PRECIOUS MOON CHARM… SOMEONE MUST HAVE STOLEN IT!!!

DON’T WORRY, COUNTESS LADA, I’M SURE THERE’S AN EXPLANATION…

HOLY MOLY! WHO ON EARTH COULD IT HAVE BEEN? LET’S GO WITH LUPO AND COMB THROUGH THE HOTEL LOOKING FOR CLUES!

1

THE SUSPECTS HE OPHELIA, T HE GHOST OF T NER: FORMER OW ACCUSE IT’S UNFAIR TO I HAD ME LIKE THAT! O WITH NOTHING TO D THAT THEFT!

TED, THE DOORMAN: I’M JUST ON GUARD DUTY, I DON’T STEAL! IF THE AMULET’S MISSING, LOOK SOMEWHERE ELSE!

CLEOPATRA, THE GUEST: ‘HOW DARE YOU! I DON’T STEAL AMULETS: I’VE OWNED THEM FOR CENTURIES!’

2

TROG, THE BODYBUILDING INSTRUCTOR: AT THE GYM, TROG LIFT S WEIGHTS – NOT SHINY THINGS!

MANNY, RY BOY: THE DELIVE ING ME A ARE YOU CALL EN ALL THESE THIEF?! BETWE E ON’T HAVE TIM SUITCASES, I D TO STEAL!

ARACNE, THE CHAMBERMA ID ON THE UPPER FL OORS: YEARS AND YEARS OF SE RVICE, AND NOW I’M BEING AC CUSED OF THEFT… IT’S MAD!

3

HERE WE ARE IN CLEOPATRA’S BEDROOM... HOLY MOLY! SHE HAS AN ENDLESS COLLECTION OF JEWELLERY; PERHAPS SHE GOT CONFUSED AND TOOK THE COUNTESS’S AMULET… LOOK HOW BEAUTIFUL THIS NECKLACE IS – THE SCARABS LOOK JUST LIKE THE REAL THING! FILL IN THE MISSING NUMBERS, INCREASING BY 100 EACH TIME.

34 134 41

__ 2

__

__ 341 __

__ 251

4

__

__

__

__

__

__

__

__ 402 __

__

734

__

__ 551

__

__ __ __

__

741 902 851

__

OOH! THERE’S A BOX FULL OF SOLID GOLD BEETLES!

58 09

READ THE NUMBER AND RANK THE BEETLES FROM LEAST VALUABLE TO MOST VALUABLE!

__

89 0

5

590 8

__ __ 95 0

8

5890

__

__

5 89

958

0

__

__

5

__

0 98

9850

0

__

__

90 85

5

LET’S HAVE A LOOK UNDER THE CARPET IN THE ROOM… MAYBE WE’LL FIND SOMETHING OTHER THAN DUST! COLOUR IN THE CARPET FOLLOWING THE INSTRUCTIONS ON THE SHEET. USE THE TOKENS ON PAGE 55 TO HELP YOU!

N 2341

5001 9150 E

A

7189

4561 3415

2145 4012

O

1500 1357

3123 7810 4100 6519

9913

1234 3201

1000

1987

L

8971

L COLOUR ALL NUMBERS WITH A 1 IN THE ONES PLACE BLUE, ALL NUMBERS WITH A 1 IN THE TENS PLACE GREEN, ALL NUMBERS WITH A 1 IN THE HUNDREDS PLACE ORANGE AND ALL NUMBERS WITH A 1 IN THE THOUSANDS PLACE PURPLE.

CLUE N.1

6

IT LOOKS AS THOUGH THERE ARE LETTERS EMBROIDERED ON THE RUG TOO. LET’S TRY TO READ THEM BELOW, STARTING WITH A AND FOLLOWING THE ARROW... PERHAPS THIS IS THE FIRST CLUE! LOOK FOR IT IN THE STICKERS, CHECK PAGES 2 AND 3 TO SEE WHICH OF THE SUSPECTS HAS THIS ITEM, AND STICK IT ON THE CLUE COLLECTION SHEET!

EVER SINCE SHE LOST HER PRICELESS TIARA SOME TIME AGO, CLEOPATRA HAS BEEN OBSESSED WITH KEEPING A METICULOUS INVENTORY OF HER GOLD, TO MAKE SURE SHE NEVER LOSES ANOTHER PIECE. SHE HAS SO MANY NECKLACES, BRACELETS, EARRINGS AND GOLD BARS THAT IT’S EASY TO LOSE COUNT!

SOLVE THE COLUMN ADDITION: USE THE PICTURE TO HELP YOU!

HUNDREDS

TENS

UNITS

7

WHAT A BEAUTIFUL MIRROR CLEOPATRA ALWAYS CARRIES WITH HER. LET’S COLOUR IN THE ENGRAVING USING THE COLOURS THAT CORRESPOND TO THE RESULTS OF THE CALCULATIONS.

600

400

900

400 + 400 =

250 + 250 =

300 + 300 =

750 – 150 =

800

400 + 500 =

150 + 150 = 1000 – 200 =

410 + 90 =

700

450 – 150 =

850 – 150 =

500 350 + 350 =

420 + 180 =

1000 – 500 = 900 – 300 =

600 + 300 = 650 – 150 =

300

610 + 90 =

200 + 200 =

550 – 150 = 250 + 350 = 1000 – 300 =

380 + 20 = 590 + 10 = 550 + 150 =

950 – 150 =

210 + 90 = 1000 – 400 =

750 + 50 =

1000 – 100 =

820 + 80 = 200 + 100 =

800 – 400 =

1000 – 700 =

450 + 150 =

950 – 50 = 150 + 350 =

8

650 – 50 =

120 + 280 = 450 + 450 =

450 – 50 =

350 + 450 =

LOOK, CLEOPATRA HAS DRAPED HER EXQUISITE EVENING VEILS OVER THE COAT HANGERS… LET’S TAKE A CLOSER LOOK AT THEM; THEY’RE TRULY FASCINATING...

SOLVE THE MULTIPLICATION PROBLEMS, AS IN THE EXAMPLE!

45 × 3 1

4

5



3 1

3

64 × 4

5 6

4  4

__ __ __ 33 × 9

3

3

59 × 3

__ __ 



9 28 × 6

2

8

__ __ __

__ 71 × 8

__ __ __

52 × 7

__ __ 

__ __ 

6

__

__

__ __ __

__ __ __

__ __ __



9

JUST LOOK AT ALL THOSE COBWEBS IN CLEOPATRA’S MAKE-UP CUPBOARD… COULD IT BE THAT THE SECRET TO HER BEAUTY LIES WITH THE SPIDERS? FINISH OFF THE COBWEBS. FOLLOW THE EXAMPLE!

24 80 10 48

6

5

4

88

2

7

32

45

11

56

60

55

64

8

8

9

72

40

3

10

16

____ ____ ____ ____ 50

____

35 ____ ____

5 ____

____ ____

49 63 28

____ ____ ____

____ ____ ____ 14

70

7 ____

____ ____ ____

42

18 99

21

81 56

63 77

____ ____ ____ ____ 45

____

9 ____

15

30

20 35

25

36 ____ ____ ____ ____

54

72

90

27

CLUE N.2 10

I THINK I CAN MAKE OUT SOMETHING WRITTEN ON THE JAR... IT COULD BE THE SECOND CLUE! LOOK FOR IT AMONG THE STICKERS, CHECK PAGES 2 AND 3 TO SEE WHICH OF THE SUSPECTS HAS THIS ITEM, AND STICK IT ON THE CLUE COLLECTION SHEET!

HAVING FINISHED SEARCHING CLEOPATRA’S ROOM, LUPO AND OMBRETTA HEAD TO THE GYM, HOPING TO FIND SOME NEW CLUES… BUT THESE MUST BE CLEOPATRA’S GYM HEADBANDS! BY ALL THE WOLVES, SHE REALLY IS ALWAYS SO STYLISH… EVEN AT THE GYM! FILL IN THE MISSING NUMBERS IN THE MULTIPLICATION TABLES!

____

9

7

____

____

16

27

21

24 32 ____

36

28

____

35

48

54

56 ____

63

____

72

____

49

80

81

56

____

____

63

99

____

11

THIS PART OF THE CELLAR IS WHERE EVERYTHING NEEDED FOR THE HOTEL RESTAURANT IS KEPT. THERE ARE LOADS OF CORKS HERE: I SUPPOSE JERARD USES THEM TO KEEP ALL HIS DELICIOUS CONCOCTIONS IN TOP CONDITION… HELP JERARD SORT THE BLACK AND WHITE CORKS INTO THE BAGS SO THAT THE SOMMELIER ALWAYS HAS A SUPPLY. DRAW THE CORKS IN THE BAGS SO THAT YOU FOLLOW THE INSTRUCTIONS!

EACH BAG CONTAINS 10 BOTTLE CAPS. REMEMBER: WHEN YOU DRAW THE BOTTLE CAPS, YOU MUST ENSURE THAT THEY MEET THE CONDITION.

BAG A: IF I PICK A CAP AT RANDOM FROM THIS BAG, I MUST BE CERTAIN THAT THE CAP IS WHITE.

A

B

BAG B: IF I PICK A CAP AT RANDOM FROM THIS BAG, I SHOULD HAVE A 50% CHANCE OF PICKING A WHITE CAP.

C

BAG C: IF I PICK A CAP AT RANDOM FROM THIS BAG, I SHOULD HAVE A GREATER CHANCE OF PICKING A BLACK CAP.

27

LOOK, JERARD IS COMPILING A LIST OF THE SPICES HE USES IN HIS COCKTAILS… HELP JERARD FINISH THE LIST! LOOK AT THE CHARTS, FILL IN THE TABLE AND ANSWER THE QUESTIONS!

CHARTS 16 14 12 10 8 6 4 2 0 CHILLI MADE FROM FIERY LAVA

GHOSTLY GRASS SCRATCH-ANDSNIFF TURMERIC

SPICES TYPE CHILLI MADE FROM FIERY LAVA GHOSTLY GRASS SCRATCH-AND-SNIFF TURMERIC CLAW OF A TROLL DARK WALNUT

28

CLAW OF A TROLL

DARK WALNUT

NUMBER

WHICH SPICE IS PRESENT IN THE GREATEST QUANTITY? ________________________________ WHICH SPICE IS PRESENT IN THE SMALLEST QUANTITY? ________________________________ HOW MANY JARS IN TOTAL? ________________________________

THERE HE IS, ARRANGING THE BOTTLES OF PREPARATIONS ON A SHELF.

BLUEBERRY AND EARTHWORM MIXTURE 150

90

DIFFERENCE

BATH DISH

HOW MANY MORE?

OPERATION: Q ADDICTION Q SUBTRACTION CALCULATION: _____________________________________________ ON THE SHELF THERE ARE______________ OF BLUEBERRY-FLAVOURED DRINK AND EARTHWORMS ON ANOTHER SHELF, HE ARRANGES THE JARS OF CINNAMON AND THE JARS OF CLOVES...

CINNAMON 128

CLOVES 85

HOW MANY BOTTLES IN TOTAL?

OPERATION: Q ADDICTION Q SUBTRACTION CALCULATION: _____________________________________________ JERARD HAS IN TOTAL ________ SPICE JARS IN HIS INVENTORY..

29

THERE’S ALSO MANNY, THE DELIVERY BOY. HE’S TIDYING AWAY THE BOXES CONTAINING THE TABLECLOTHS MADE BY THE WEAVER TARANTULAS… THEY’RE SO BEAUTIFULLY CRUMPLED! MANNY IS TIDYING AWAY THE BOXES OF TABLECLOTH ROW: 3

4

4

4

HOW MANY BOXES?

HOW MANY BOXES ARE THERE? _______ THEN MANNY ASKS SOME TROLLS FOR HELP TO CARRY THE CUTLERY INTO THE DINING ROOM.

?

?

?

?

?

?

CUTLERY IN TOTAL: 18

HOW MANY PIECES OF CUTLERY DOES EACH TROLL RECEIVE?_______

CLUE N.7 30

HAVE YOU NOTICED THE LABEL ON THE BOX? IT COULD BE THE SEVENTH CLUE! LOOK FOR IT AMONG THE STICKERS, CHECK PAGES 2 AND 3 TO SEE WHICH OF THE SUSPECTS HAS THIS ITEM AND STICK IT ON THE CLUE COLLECTION SHEET!

MANNY NOW HAS TO SORT OUT THE CAKES FOR TONIGHT… LET’S HOPE THEY’VE GONE PROPERLY MOULDY IN THE CELLAR! TAKE A LOOK AT THE CAKES AND ANSWER THE QUESTIONS!

CAKE 1

CAKE 2

CAKE 3

1. WHICH PART OF THE SECOND CAKE WAS MOVED?

__________

2. HOW MUCH OF THE SECOND CAKE IS STILL THERE?

__________

3. IF THE GOALKEEPER EATS TWO SQUARES OF THE THIRD CAKE, WHAT FRACTION HAS HE EATEN?

__________

4. HOW MUCH OF THE THIRD CAKE IS LEFT?

__________

31

MANNY IS CURRENTLY PREPARING THE TRAYS OF DRINKS FOR THE GRAND GALA… LOOK AT THE FRACTIONS AND WRITE DOWN THE CORRECT ONE!

MANNY IS CARRYING A JUG CONTAINING 12 LITRES OF MUMMY JUICE. 2

AS HE MAKES HIS WAY DOWN THE DARK CORRIDOR, HE KNOCKS SOME OVER 6 .

HOW MUCH MUMMY JUICE IS LEFT IN THE JUG?________ MISSING PARTS: 2 6

REMAINING PARTS: ?

TOTAL: 12 l

MANNY HAS A JUG CONTAINING 8 LITRES OF VAMPIRE LEMONADE. 3 A MISCHIEVOUS BAT SUDDENLY APPEARS AND KNOCKS IT OVER 4 . HOW MANY LITRES OF LEMONADE ARE LEFT IN THE JUG?________ MISSING PARTS: 3 4 REMAINING PARTS: ?

TOTAL: 8 l

MANNY HAS TO MAKE SURE THAT GHOST COLA GIVES PEOPLE THE CREEPS 1

IT’S JUST RIGHT, SO HE SIPS 3 LITRES OF IT TO CHECK HOW FRESH IT IS. HOW MUCH IS LEFT? PORTION CONSUMED: REMAINING PARTS: ? 1 3

TOTAL: 6 l

32

WELL DONE, MANNY! THERE ARE STILL A FEW DRINKS LEFT TO SORT OUT, AND THEN HE CAN FINALLY MOVE EVERYTHING INTO THE DINING ROOM. LET’S HOPE HE DOESN’T CAUSE ANY MORE DISASTERS! LOOK AT THE PICTURES AND WORK OUT THE VALUE OF THE CONTAINERS. ?

TOTAL: 12 l

HOW MANY LITRES DOES 1

HOLD?

?

TOTAL: 8 l

HOW MANY LITRES DOES 1

HOLD?

NOW MANNY IS PUTTING SOME CONTAINERS INTO THE TROLLEY:

HOW MANY LITERS ARE THERE?________

CLUE N.8 LET’S CHECK THE SHELVES AGAIN... HAVE YOU FOUND THE EIGHTH CLUE? LOOK FOR IT AMONG THE STICKERS, CHECK PAGES 2 AND 3 TO SEE WHICH OF THE SUSPECTS HAS THIS ITEM AND STICK IT ON THE CLUE COLLECTION SHEET!

33

AFTER CAREFULLY CHECKING THE SUSPECTS’ PAGES, OMBRETTA AND LUPO REALISE THAT ALL THE CLUES POINT TO __________________.

BUT THEIR MISSION ISN’T OVER YET…

GREAT WORK! WE’VE FIGURED OUT WHO STOLE THE AMULET… BUT NOW WE NEED TO FIND OUT WHERE IT’S HIDDEN! LET’S GRAB THE HOTEL MAP AND CHECK WHICH ROOMS WE HAVEN’T SEARCHED YET!

… SO, WE STILL NEED THE BREAKFAST ROOM, THE CREATIVE CLUB’S ATTIC AND THE LUGGAGE ROOM. BUT WHERE DO WE START?

WOLF! WHAT’S BEHIND THE ARMCHAIR?!

34

WOW! IT’S DEFINITELY A CLUE! COME WITH ME, I KNOW WHERE WE NEED TO START LOOKING… THAT ITEM IS USED IN THE VERY FIRST ROOM WE NEED TO CHECK… CHECK THE MAP TO SEE WHICH PAGE WE NEED TO GO TO!

HERE WE ARE IN THE BREAKFAST ROOM. I RECKON WE COULD STOP FOR A MID-MORNING SNACK… WHAT DO YOU SAY? LOOK AT THAT, THE SPECIAL EDITION OF *GAZZETTINO DELL’ENIGMISTICA*. LET’S FLICK THROUGH IT TOGETHER AND DO A FEW PUZZLES TO TAKE OUR MINDS OFF THE INVESTIGATION! READ ABOUT THESE CHALLENGES IN THE PAGES OF *IL GAZZETTINO*. GIVE THEM A GO!

•

IMAGINE TWO STRAIGHT LINES THAT NEVER INTERSECT, WHILST ALWAYS MAINTAINING THE SAME DISTANCE BETWEEN THEM. HOW ARE THESE LINES DEFINED? Q INTERSECTING LINES

Q PERPENDICULAR LINES

Q PARALLEL LINES Q CONSECUTIVE LINES • IMAGINE SWITCHING ON A TORCH: THE LIGHT EMANATES FROM THE BULB (A SPECIFIC POINT) AND TRAVELS STRAIGHT OUT INTO THE DARKNESS, STRETCHING ON FOREVER. WHAT IS THIS BEAM OF LIGHT? Q A SEGMENT

Q A HALF-LINE

Q A LINE Q AN ANGLE • IF TWO STRAIGHT LINES INTERSECT TO FORM FOUR ANGLES THAT ARE EXACTLY EQUAL TO ONE ANOTHER (RIGHT ANGLES), HOW ARE THEY DEFINED? Q PARALLEL LINES Q PERPENDICULAR LINES Q HORIZONTAL LINES

Q CURVED LINES

• LOOK AT THE TRACKS OF A TRAIN ON A STRAIGHT STRETCH: THEY RUN SIDE BY SIDE AND NEVER CROSS. IN GEOMETRY, THESE TWO LINES ARE CALLED: Q PERPENDICULAR LINES Q LINES THAT “MEET” EACH OTHER” Q R PARALLEL LINES

Q INTERSECTING LINESI

35

BUT LOOK AT THAT… WHOLEMEAL CHOCOLATE AND HONEY WORMS! I’M ABSOLUTELY MAD ABOUT THEM! JUST LOOK AT THE TRAILS OF DROOL THEY’VE LEFT ON THE TRAY! LOOK AT THE LINES AND TICK THE RIGHT COLUMNS!

CLOSED CURVE

BROKEN

MIXED

SIMPLE

WOVEN

ok

36

WE’VE MADE SO MANY CRUMBS! LET’S HAVE FUN CONNECTING THEM AND MAKING SHAPES! JOIN THE CRUMBS TOGETHER TO FORM THE TRIANGLES SHOWN. USE A RULER!

EQUILATERAL TRIANGLE

ISOSCELES TRIANGLE

SCALENE TRIANGLE

ACUTE-ANGLED TRIANGLE

OBTUSE-ANGLED TRIANGLE

RECTANGULAR TRIANGLE

37

MONSTROUS PROBLEMS AT HOTEL DE TENEBRIS PRACTISING MATHEMATICAL SKILLS WITH… A BIT OF A THRILL The ‘Monstrous Problems at the Hotel De Tenebris’ series uses the engaging and immersive setting of a mystery story to make children feel brave and resourceful, offering games and exercises that stimulate the learning process whilst strengthening the mathematical skills underpinning problem-solving. It is, in fact, through problem-solving that children develop a deeper understanding of mathematical concepts and appreciate the relevance and usefulness of mathematics.

Problem-solving in mathematics supports the development of the ability to: • think creatively, critically and logically; • structure and organise; • process information; • investigate and understand the world around us.

It is important to avoid placing too much emphasis on skills and procedures at the expense of problem-solving and intuition, but above all — a choice that has guided this series — to train all four specific pro-

blem-solving skills: understanding, planning, solving and monitoring. Furthermore, it is essential to support visual-spatial memory, recently recognised as a key factor in mathematical problem-solving ability: for this reason, the series utilises various tools from the Singapore Method: an approach that includes the CPA progression (Concrete, Pictorial, Abstract), number bonds, bar models and mental maths (Friends of Numbers and Doubles of Numbers). Together with Ombretta, Lupo and the ‘monstrous’ characters of the Hotel De Tenebris, primary school children can learn maths whilst having fun, tackling little challenges with numbers, calculations and geometric shapes in a truly exciting ‘game-book’!

Webography (links accessed on 17 April 2026) https://www.generationready.com/white-papers/mathematics-as-a-complex-problem-solving-activity/ https://www.sadlier.com/school/sadlier-math-blog/polyas-problem-solving-steps-finding-unknowns-elementary-and-middle-school https://www.singaporemath.com/pages/what-is-singapore-math

Index of activities by topic Reading, writing and comparing numbers up to 10,000 Pages

4

5

Place value of the digits (u, t, h, th) Pages

6

7

Addition and subtraction (inverse operations, number bonds, repeated operations, number lines) Pages

7

8

14 15 17

Multiplication and division (inverse operations, number bonds, numerical relationships) Pages

9

10 16 18

Mixed multiplication tables Pages

11 12 13

Estimated quantities and results Pages

54

19

Decimal fractions and decimal numbers Pages 20

21 22 23 24 25

26

Understanding simple probability situations by comparing quantities Pages 27 Problems involving natural numbers and fractions, with the aid of graphs and bar charts Pages

28 29 30 31 32 33

Points, lines, line segments, straight lines and half-lines Pages

35

Open, closed, intertwined lines Pages

36

Polygons: other shapes, characteristics of polygons Pages 37

38 39

Solid shapes: cube, rectangular prism, prism, sphere, cylinder, cone Pages 44 Symmetry and symmetrical shapes Pages 45 Units of length (mm, cm, m, km) Pages 46 47 Problems with units of measurement (length, weight, capacity) Pages 48 49 50 51 Problem solving (understanding, planning, implementation, monitoring) Pages 40

41 42 43

A LI

TR PA A

manca

NN

OG

Y

AR

MA

TR

C LE O

TE D

OFE

SUSPECTS AND GATHERING EVIDENCE

AC

NE

ATELIER OF CREATIVES p. 40

BREAKFAST ROOM p. 35

CLEOPATRA’S ROOM p. 4

GYM p. 11

LUGGAGE STORAGE p. 44 CELLAR p. 20

© 2026 Erickson