🔎 Mr. Nappi's Missing PencilsGrade 9Reading: grades 7-9Fractions of a numberWord problemsBar modelsMulti-step word problems
The Case of Mr. Nappi's Missing Pencils
Disaster has struck Room 204! Mr. Nappi's prized vault of premium yellow Ticonderoga pencils has been completely cleaned out. Only a math detective can solve the trail of graphite clues and find the culprit.
Suspects
Possible suspects
Cross off a row as each clue rules it out. On screen, tap a row.
21 of 21 still in play
| Name | Hallway Excuse | Looting Style | Writing Hand | Backpack Color | Distraction Trick |
|---|---|---|---|---|---|
| Ian | guidance meeting | backpack sweep | right handed | crimson red | dropped hallway binder |
| Valerie | locker runs | backpack sweep | left handed | crimson red | dropped hallway binder |
| Zoe | guidance meeting | locker dumping | right handed | crimson red | crinkly chip bag |
| Gavin | locker runs | hoodie pocketing | left handed | navy blue | dropped hallway binder |
| Marcus | bathroom pass | pencil case raid | left handed | crimson red | crinkly chip bag |
| Danielle | guidance meeting | backpack sweep | right handed | neon green | crinkly chip bag |
| Lana | guidance meeting | locker dumping | right handed | crimson red | squeaky desk chair |
| Fiona | bathroom pass | pencil case raid | right handed | crimson red | dropped hallway binder |
| Ethan | water fountain | backpack sweep | left handed | crimson red | dropped hallway binder |
| Haley | water fountain | backpack sweep | right handed | crimson red | dropped hallway binder |
| Wyatt | locker runs | backpack sweep | right handed | navy blue | squeaky desk chair |
| Nadia | guidance meeting | backpack sweep | right handed | navy blue | dropped hallway binder |
| Kyle | bathroom pass | backpack sweep | right handed | crimson red | dropped hallway binder |
| Julia | bathroom pass | locker dumping | left handed | neon green | crinkly chip bag |
| Owen | bathroom pass | hoodie pocketing | left handed | neon green | crinkly chip bag |
| Paige | bathroom pass | binder stuffing | left handed | neon green | squeaky desk chair |
| Ulysses | nurse visit | binder stuffing | right handed | neon green | squeaky desk chair |
| Riley | guidance meeting | pencil case raid | left handed | navy blue | dropped hallway binder |
| Sam | nurse visit | backpack sweep | right handed | crimson red | crinkly chip bag |
| Quinn | guidance meeting | hoodie pocketing | right handed | navy blue | dropped hallway binder |
| Tara | nurse visit | backpack sweep | right handed | crimson red | dropped hallway binder |
Clue 1
Fractions of a number
To track the bandit's path, we analyze the classroom supply log. The bandit took several boxes of pencils, handed some out to accomplices, and hid the rest, requiring a multi-step calculation to find the true starting count.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
T
5
57
17
43
2
13
44
59
T
5
44
59
44
13
47
T
5
34
60
17
2
27
17
13
23
59
54
23
2
60
17
32
2
59
44
1/4 of 20 =T
2/6 of 162 =L
2/6 of 129 =B
2/4 of 120 =S
1/8 of 136 =E
2/10 of 160 =R
1/4 of 52 =N
1/5 of 115 =C
5/10 of 118 =I
3/6 of 114 =H
1/3 of 132 =D
2/4 of 4 =A
1/3 of 141 =O
2/8 of 108 =P
2/4 of 68 =U
0/15 letters found
Clue 2
Word problems
A witness in the hall remembers seeing someone rushing past the lockers with bundles of writing utensils. We can figure out the exact number of stolen pencils by solving this word problem.
Solve each problem to learn its letter, then write the letters in the boxes to fill in the missing word.
Awitnesssawthevillainwas .
R
80
68
52
85
97
85
62
88
D
E
D
There were 108 protractors. 28 were used up. How many protractors are left?R
Mr. Nappi found 12 calculators yesterday and 56 more today. How many calculators in all?I
There were 121 rulers. 24 were used up. How many rulers are left?T
Mr. Nappi found 11 protractors yesterday and 41 more today. How many protractors in all?G
Mr. Nappi found 49 erasers yesterday and 36 more today. How many erasers in all?H
Mr. Nappi found 58 calculators yesterday and 30 more today. How many calculators in all?N
Mr. Nappi found 43 protractors yesterday and 19 more today. How many protractors in all?A
0/7 letters found
Clue 3
Bar model word problems
Mr. Nappi draws a bar model on the board to compare his morning pencil stash with the empty boxes left behind. Visualizing these ratios reveals the culprit's getaway timing.
Draw a bar model to solve each word problem. Its answer reveals a letter — write the letters in the boxes to fill in the missing word.
Someonescaredthevillainoffwith .
D
35
62
75
40
40
138
D
35
27
63
L
L
W
63
Y
B
I
N
D
35
138
62
Mr. Nappi has 5 times as many pencils as a teammate. The teammate has 7 pencils. How many pencils does Mr. Nappi have?
draw a bar model
Answer:→D
Mr. Nappi shares 189 erasers equally among 3 teams. How many erasers does each team get?
draw a bar model
Answer:→A
Mr. Nappi used 1/2 of the calculators on the first day. The other 69 calculators were used the next day. How many calculators were there in all?
draw a bar model
Answer:→E
One group collected 45 rulers and another group collected 17 rulers. How many rulers in all?
draw a bar model
Answer:→R
Mr. Nappi has 3 times as many pencils as a teammate. The teammate has 9 pencils. How many pencils does Mr. Nappi have?
draw a bar model
Answer:→H
Mr. Nappi used 1/2 of the calculators on the first day. The other 20 calculators were used the next day. How many calculators were there in all?
draw a bar model
Answer:→P
The red team has 108 protractors and the blue team has 33 protractors. How many more protractors does the red team have?
draw a bar model
Answer:→O
0/7 letters found
Clue 4
Multi-step word problems
We find a discarded backpack containing only a fraction of the original stolen stash. Calculating this fraction points us to the specific hallway where the loot was divided.
Solve each problem to learn its letter, then write the letters in the boxes to fill in the missing word.
Astrandof hairturnedupatthescene.
C
22
13
25
59
49
19
11
13
E
D
There were 84 calculators in all. 2 The Math Club used 20 calculators each. The other 2 The Math Club shared the rest equally. How many calculators did each of the other The Math Club get?C
There were 378 protractors in all. 35 protractors were set aside. The rest were shared equally among 7 The Math Club. How many protractors did each get?S
Mr. Nappi earned 2 protractors in each of 4 rounds, plus 66 bonus protractors. Then 15 protractors were lost. How many protractors are left?M
Mr. Nappi earned 4 protractors in each of 2 rounds, plus 13 bonus protractors. Then 8 protractors were lost. How many protractors are left?R
Mr. Nappi earned 2 calculators in each of 5 rounds, plus 17 bonus calculators. Then 2 calculators were lost. How many calculators are left?I
Mr. Nappi earned 3 rulers in each of 2 rounds, plus 28 bonus rulers. Then 15 rulers were lost. How many rulers are left?O
Mr. Nappi collected 16 protractors in the morning and 28 protractors in the afternoon, then split them equally among 4 The Math Club. How many protractors did each get?N
0/7 letters found
Clue 5
Fractions of a number — the last clue
A final clue comes from the lost and found box, where another fraction of the missing collection was hidden. Finding this precise fraction narrows down our suspect list.
First solve each problem. Then find each answer in the list below and cross that sentence out. One sentence will be left — that's exactly what the villain did!
Step 1 — solve these
3/8 of 8 = ?
2/4 of 16 = ?
4/8 of 14 = ?
3/8 of 24 = ?
5/10 of 22 = ?
4/8 of 8 = ?
1/8 of 8 = ?
2/10 of 25 = ?
2/4 of 4 = ?
2/5 of 25 = ?
1/4 of 48 = ?
Step 2 — cross out the sentence with each answer
1.The villain nabbed the dry erase markers, then dropped a broken lead piece.
2.The villain nabbed the dry erase markers, then ran down the main corridor.
3.The villain emptied the pencil drawer, then left a trail of shavings.
4.The villain stole the golden sharpener, then ran down the main corridor.
5.The villain swiped the mechanical pencils, then ran down the main corridor.
6.The villain plundered the spare erasers, then left a trail of shavings.
7.The villain nabbed the dry erase markers, then left a trail of shavings.
8.The villain stole the golden sharpener, then left a trail of shavings.
9.The villain nabbed the dry erase markers, then hid the evidence in a locker.
10.The villain emptied the pencil drawer, then ran down the main corridor.
11.The villain emptied the pencil drawer, then smudged the whiteboard clean.
12.The villain stole the golden sharpener, then hid the evidence in a locker.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of Mr. Nappi's Missing Pencils
Culprit: Ian (guidance meeting · backpack sweep · right handed · crimson red · dropped hallway binder)
- Clue 1 (Fractions of a number): "THE BANDIT DID NOT USE A PENCIL CASE RAID"1/4 of 20 = 5 (T) · 2/6 of 162 = 54 (L) · 2/6 of 129 = 43 (B) · 2/4 of 120 = 60 (S) · 1/8 of 136 = 17 (E) · 2/10 of 160 = 32 (R) · 1/4 of 52 = 13 (N) · 1/5 of 115 = 23 (C) · 5/10 of 118 = 59 (I) · 3/6 of 114 = 57 (H) · 1/3 of 132 = 44 (D) · 2/4 of 4 = 2 (A) · 1/3 of 141 = 47 (O) · 2/8 of 108 = 27 (P) · 2/4 of 68 = 34 (U)
- Clue 2 (Word problems): "RIGHT HANDED"There were 108 protractors. 28 were used up. How many protractors are left? = 80 (R) · Mr. Nappi found 12 calculators yesterday and 56 more today. How many calculators in all? = 68 (I) · There were 121 rulers. 24 were used up. How many rulers are left? = 97 (T) · Mr. Nappi found 11 protractors yesterday and 41 more today. How many protractors in all? = 52 (G) · Mr. Nappi found 49 erasers yesterday and 36 more today. How many erasers in all? = 85 (H) · Mr. Nappi found 58 calculators yesterday and 30 more today. How many calculators in all? = 88 (N) · Mr. Nappi found 43 protractors yesterday and 19 more today. How many protractors in all? = 62 (A)
- Clue 3 (Bar model word problems): "DROPPED HALLWAY BINDER"Mr. Nappi has 5 times as many pencils as a teammate. The teammate has 7 pencils. How many pencils does Mr. Nappi have? = 35 (D) · Mr. Nappi shares 189 erasers equally among 3 teams. How many erasers does each team get? = 63 (A) · Mr. Nappi used 1/2 of the calculators on the first day. The other 69 calculators were used the next day. How many calculators were there in all? = 138 (E) · One group collected 45 rulers and another group collected 17 rulers. How many rulers in all? = 62 (R) · Mr. Nappi has 3 times as many pencils as a teammate. The teammate has 9 pencils. How many pencils does Mr. Nappi have? = 27 (H) · Mr. Nappi used 1/2 of the calculators on the first day. The other 20 calculators were used the next day. How many calculators were there in all? = 40 (P) · The red team has 108 protractors and the blue team has 33 protractors. How many more protractors does the red team have? = 75 (O)
- Clue 4 (Multi-step word problems): "CRIMSON RED"There were 84 calculators in all. 2 The Math Club used 20 calculators each. The other 2 The Math Club shared the rest equally. How many calculators did each of the other The Math Club get? = 22 (C) · There were 378 protractors in all. 35 protractors were set aside. The rest were shared equally among 7 The Math Club. How many protractors did each get? = 49 (S) · Mr. Nappi earned 2 protractors in each of 4 rounds, plus 66 bonus protractors. Then 15 protractors were lost. How many protractors are left? = 59 (M) · Mr. Nappi earned 4 protractors in each of 2 rounds, plus 13 bonus protractors. Then 8 protractors were lost. How many protractors are left? = 13 (R) · Mr. Nappi earned 2 calculators in each of 5 rounds, plus 17 bonus calculators. Then 2 calculators were lost. How many calculators are left? = 25 (I) · Mr. Nappi earned 3 rulers in each of 2 rounds, plus 28 bonus rulers. Then 15 rulers were lost. How many rulers are left? = 19 (O) · Mr. Nappi collected 16 protractors in the morning and 28 protractors in the afternoon, then split them equally among 4 The Math Club. How many protractors did each get? = 11 (N)
- Clue 5 (Fractions of a number): surviving statement (box 6) → Ian3/8 of 8 = 3 · 2/4 of 16 = 8 · 4/8 of 14 = 7 · 3/8 of 24 = 9 · 5/10 of 22 = 11 · 4/8 of 8 = 4 · 1/8 of 8 = 1 · 2/10 of 25 = 5 · 2/4 of 4 = 2 · 2/5 of 25 = 10 · 1/4 of 48 = 12
About this mystery
- Grade level
- Grade 9 math
- Math topics
- Fractions of a number, Word problems, Bar models, Multi-step word problems
- Reading level
- grades 7-9
- Theme
- The Case of Mr. Nappi's Missing Pencils — set in Room 204
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects