Grade 1Reading: grades 1-2AdditionSubtractionMultiplicationSkip countingDivision
The Treehouse Fort Mystery
Someone snuck into the club treehouse and took the secret snack box! Solve the math clues to find out who did it.
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 | Club Skill | Gear Item | Dominant Hand | Hair Style | Scared By |
|---|---|---|---|---|---|
| Milo | Whistle Blowing | Brass Bell | Left Handed | Smooth Hair | Squeaky Toys |
| Ben | Map Reading | Pocket Telescope | Left Handed | Spiky Hair | Squeaky Toys |
| Max | Whistle Blowing | Magnifying Glass | Left Handed | Curly Hair | Party Horns |
| Cora | Whistle Blowing | Bright Flashlight | Right Handed | Spiky Hair | Party Horns |
| Toby | Whistle Blowing | Magnifying Glass | Right Handed | Smooth Hair | Squeaky Toys |
| Maya | Whistle Blowing | Bright Flashlight | Left Handed | Spiky Hair | Party Horns |
| Finn | Map Reading | Magnifying Glass | Right Handed | Curly Hair | Party Horns |
| Leo | Shadow Sneaking | Pocket Telescope | Left Handed | Smooth Hair | Party Horns |
| Owen | Rope Climbing | Bright Flashlight | Right Handed | Smooth Hair | Squeaky Toys |
| Ava | Shadow Sneaking | Brass Bell | Left Handed | Smooth Hair | Party Horns |
| Mia | Whistle Blowing | Wooden Compass | Right Handed | Smooth Hair | Party Horns |
| Ella | Rope Climbing | Pocket Telescope | Right Handed | Smooth Hair | Party Horns |
| Lily | Rope Climbing | Brass Bell | Right Handed | Curly Hair | Bubble Blowers |
| Eli | Whistle Blowing | Brass Bell | Left Handed | Smooth Hair | Party Horns |
| Sam | Tree Hopping | Bright Flashlight | Right Handed | Curly Hair | Squeaky Toys |
| Emma | Rope Climbing | Brass Bell | Left Handed | Curly Hair | Party Horns |
| Noah | Tree Hopping | Brass Bell | Left Handed | Spiky Hair | Party Horns |
| Joy | Shadow Sneaking | Magnifying Glass | Right Handed | Smooth Hair | Party Horns |
| Nora | Map Reading | Pocket Telescope | Left Handed | Smooth Hair | Bubble Blowers |
| Zoe | Rope Climbing | Brass Bell | Right Handed | Smooth Hair | Party Horns |
| Kai | Shadow Sneaking | Brass Bell | Right Handed | Smooth Hair | Party Horns |
Clue 1
Addition
We counted all the juice boxes added to the snack bin.
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
15
3
10
19
16
11
5
8
T
15
5
13
10
14
11
13
T
15
4
16
7
7
6
16
17
13
13
5
10
11
4
13
2
20
16
14
14
7 + 8 =T
4 + 2 =Y
6 + 11 =W
4 + 7 =N
9 + 7 =A
1 + 1 =M
10 + 3 =O
3 + 1 =C
4 + 3 =R
4 + 1 =D
11 + 8 =B
8 + 6 =S
6 + 14 =P
5 + 3 =I
2 + 1 =H
4 + 6 =E
0/16 letters found
Clue 2
Subtraction
We took away the broken pinecones from our stash.
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
3
2
13
15
4
10
16
1
T
3
6
13
12
T
3
5
18
1
10
T
3
8
12
18
19
9
T
3
2
13
1
18
18
1
17
2
T
3
2
4
10
16
12 - 9 =T
8 - 2 =L
18 - 1 =G
20 - 2 =R
18 - 3 =B
8 - 7 =I
7 - 5 =H
17 - 9 =S
20 - 1 =O
13 - 4 =M
8 - 3 =P
12 - 2 =N
13 - 9 =A
14 - 1 =E
16 - 4 =F
19 - 3 =D
0/16 letters found
Clue 3
Multiplication facts (1-12)
We lined up our flashlights in equal groups.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
P
96
108
6
10
72
54
77
6
21
35
14
108
48
84
10
54
84
70
108
21
48
44
10
6
11
21
108
1
108
72
12 × 8 =P
12 × 9 =A
1 × 1 =W
4 × 11 =I
5 × 7 =S
4 × 12 =D
11 × 1 =U
3 × 7 =N
7 × 12 =E
7 × 10 =B
3 × 2 =R
7 × 11 =O
1 × 10 =T
6 × 12 =Y
7 × 2 =M
9 × 6 =H
0/16 letters found
Clue 4
Skip counting
We counted all the path markers by twos.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
A
100
20
42
140
140
9
16
20
9
70
A
100
8
28
140
30
16
A
100
15
70
80
A
100
20
110
33
30
9
140
8
9
16
33
70
140
22
33
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120A
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48M
Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12N
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24S
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100W
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, ___, 75, 80R
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, ___, 35, 40F
Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15T
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ___, 36, 39E
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, ___, 18, 21I
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, ___, 30, 32D
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160O
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20H
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130L
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26P
0/15 letters found
Clue 5
Division facts (1-12) — the last clue
We shared our trail mix equally into small bags.
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
108 ÷ 12 = ?
60 ÷ 5 = ?
25 ÷ 5 = ?
8 ÷ 8 = ?
33 ÷ 3 = ?
36 ÷ 6 = ?
20 ÷ 5 = ?
64 ÷ 8 = ?
20 ÷ 2 = ?
2 ÷ 1 = ?
28 ÷ 4 = ?
Step 2 — cross out the sentence with each answer
1.The villain blew a loud whistle, then shined a bright flashlight.
2.The villain snuck through the shadows, then shined a bright flashlight.
3.The villain climbed the high rope, then looked through a pocket telescope.
4.The villain climbed the high rope, then used a magnifying glass.
5.The villain snuck through the shadows, then used a magnifying glass.
6.The villain blew a loud whistle, then dropped a wooden compass.
7.The villain hopped across tree branches, then shined a bright flashlight.
8.The villain climbed the high rope, then dropped a wooden compass.
9.The villain snuck through the shadows, then rang a brass bell.
10.The villain read a secret map, then dropped a wooden compass.
11.The villain read a secret map, then shined a bright flashlight.
12.The villain climbed the high rope, then rang a brass bell.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Treehouse Fort Mystery
Culprit: Ella (Rope Climbing · Pocket Telescope · Right Handed · Smooth Hair · Party Horns)
- Clue 1 (Addition): "THE BANDIT DOES NOT CARRY A WOODEN COMPASS"7 + 8 = 15 (T) · 4 + 2 = 6 (Y) · 6 + 11 = 17 (W) · 4 + 7 = 11 (N) · 9 + 7 = 16 (A) · 1 + 1 = 2 (M) · 10 + 3 = 13 (O) · 3 + 1 = 4 (C) · 4 + 3 = 7 (R) · 4 + 1 = 5 (D) · 11 + 8 = 19 (B) · 8 + 6 = 14 (S) · 6 + 14 = 20 (P) · 5 + 3 = 8 (I) · 2 + 1 = 3 (H) · 4 + 6 = 10 (E)
- Clue 2 (Subtraction): "THE BANDIT LEFT PRINTS FROM THEIR RIGHT HAND"12 - 9 = 3 (T) · 8 - 2 = 6 (L) · 18 - 1 = 17 (G) · 20 - 2 = 18 (R) · 18 - 3 = 15 (B) · 8 - 7 = 1 (I) · 7 - 5 = 2 (H) · 17 - 9 = 8 (S) · 20 - 1 = 19 (O) · 13 - 4 = 9 (M) · 8 - 3 = 5 (P) · 12 - 2 = 10 (N) · 13 - 9 = 4 (A) · 14 - 1 = 13 (E) · 16 - 4 = 12 (F) · 19 - 3 = 16 (D)
- Clue 3 (Multiplication facts (1-12)): "PARTY HORNS MADE THE BANDIT RUN AWAY"12 × 8 = 96 (P) · 12 × 9 = 108 (A) · 1 × 1 = 1 (W) · 4 × 11 = 44 (I) · 5 × 7 = 35 (S) · 4 × 12 = 48 (D) · 11 × 1 = 11 (U) · 3 × 7 = 21 (N) · 7 × 12 = 84 (E) · 7 × 10 = 70 (B) · 3 × 2 = 6 (R) · 7 × 11 = 77 (O) · 1 × 10 = 10 (T) · 6 × 12 = 72 (Y) · 7 × 2 = 14 (M) · 9 × 6 = 54 (H)
- Clue 4 (Skip counting): "A SMOOTH STRAND OF HAIR WAS LEFT ON THE ROPE"Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120 = 100 (A) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48 = 42 (M) · Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12 = 8 (N) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24 = 20 (S) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100 = 80 (W) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, ___, 75, 80 = 70 (R) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, ___, 35, 40 = 30 (F) · Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15 = 9 (T) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ___, 36, 39 = 33 (E) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, ___, 18, 21 = 15 (I) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, ___, 30, 32 = 28 (D) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160 = 140 (O) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20 = 16 (H) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130 = 110 (L) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26 = 22 (P)
- Clue 5 (Division facts (1-12)): surviving statement (box 3) → Ella108 ÷ 12 = 9 · 60 ÷ 5 = 12 · 25 ÷ 5 = 5 · 8 ÷ 8 = 1 · 33 ÷ 3 = 11 · 36 ÷ 6 = 6 · 20 ÷ 5 = 4 · 64 ÷ 8 = 8 · 20 ÷ 2 = 10 · 2 ÷ 1 = 2 · 28 ÷ 4 = 7
About this mystery
- Grade level
- Grade 1 math
- Math topics
- Addition, Subtraction, Multiplication, Skip counting, Division
- Reading level
- grades 1-2
- Theme
- The Treehouse Fort Mystery — set in Whispering Woods Treehouse
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects