Grade 3Reading: grades 1-2AdditionPlace valueSkip countingRoundingDivision
The Great Treehouse Mystery
Someone took the Golden Walkie Talkie from the secret treetop fort! The Treehouse Rangers need your help to find the culprit and bring back the camp prize.
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 | climbing gear | pocket gadget | writing hand | helmet color | favorite snack |
|---|---|---|---|---|---|
| Ben | rope ladder | mini camera | right handed | blue helmet | cheese sticks |
| Jax | zipline pulley | mini camera | right handed | green helmet | cheese sticks |
| Leo | bungee cord | spy whistle | right handed | green helmet | apple slices |
| Mac | grappling hook | laser pointer | left handed | blue helmet | cheese sticks |
| Zoe | bungee cord | decoder ring | left handed | green helmet | apple slices |
| Joy | rope ladder | decoder ring | left handed | green helmet | cheese sticks |
| Luna | grappling hook | decoder ring | right handed | red helmet | apple slices |
| Hugo | zipline pulley | laser pointer | left handed | blue helmet | cheese sticks |
| Gigi | zipline pulley | flash light | left handed | blue helmet | juice boxes |
| Toby | suction boots | decoder ring | left handed | green helmet | apple slices |
| Kai | suction boots | laser pointer | left handed | green helmet | cheese sticks |
| Ava | grappling hook | flash light | left handed | blue helmet | cheese sticks |
| Otis | suction boots | mini camera | right handed | green helmet | cheese sticks |
| Nico | zipline pulley | mini camera | right handed | red helmet | cheese sticks |
| Eli | grappling hook | mini camera | left handed | green helmet | cheese sticks |
| Sam | rope ladder | mini camera | left handed | red helmet | juice boxes |
| Finn | zipline pulley | mini camera | right handed | blue helmet | apple slices |
| Sasha | zipline pulley | flash light | left handed | blue helmet | cheese sticks |
| Roy | rope ladder | spy whistle | left handed | green helmet | cheese sticks |
| Cody | zipline pulley | flash light | right handed | red helmet | juice boxes |
| Pip | zipline pulley | flash light | left handed | green helmet | cheese sticks |
Clue 1
Addition
We need to find the total number of muddy footprints left on the wooden bridge. Let us add the tracks from both sides of the river.
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
428
455
692
879
924
550
775
692
879
775
217
692
476
925
217
T
428
455
924
368
692
924
476
479
268
411
455
550
476
T
428
934
692
199 + 229 =T
116 + 101 =O
307 + 468 =D
471 + 454 =N
357 + 522 =R
305 + 171 =S
618 + 316 =L
408 + 284 =E
189 + 222 =W
149 + 306 =H
224 + 255 =P
221 + 147 =V
309 + 241 =I
157 + 111 =Y
329 + 595 =A
0/15 letters found
Clue 2
Place value
The lock on the secret hollow tree uses base ten blocks to show the code. Let us look at the tens and ones to read the secret number.
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
60
9000
8000
20
2000
700
3000
8000
20
1000
20
700
T
60
8000
800
1000
700
T
60
9000
T
60
9000
8000
700
20
30
8000
90
T
60
9000
2000
5000
3000
What is the value of the 6 in 760?T
What is the value of the 8 in 38,462?E
What is the value of the 2 in 1,926?R
What is the value of the 1 in 1,050?W
What is the value of the 7 in 706?I
What is the value of the 3 in 13,111?D
What is the value of the 9 in 194?F
What is the value of the 2 in 62,705?A
What is the value of the 3 in 539?L
What is the value of the 8 in 834?S
What is the value of the 9 in 59,237?H
What is the value of the 5 in 5,821?N
0/12 letters found
Clue 3
Skip counting
The escape path goes across giant leaves in the pond. Let us skip count by twos to hop safely to the other side.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
W
8
130
15
65
20
12
18
25
35
130
130
30
130
30
70
110
25
100
W
8
45
50
40
40
130
45
30
70
35
130
45
130
Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12W
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, ___, 33, 36S
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, ___, 55, 60A
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45H
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130I
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55R
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150E
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, ___, 21, 24D
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, ___, 14, 16N
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120K
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75O
Skip-count by 10s. Fill the blank: 10, 20, 30, ___, 50, 60P
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24U
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, ___, 75, 80T
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, ___, 18, 21F
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35C
0/16 letters found
Clue 4
Rounding
We found a small tracker device but the screen is cracked. It only shows numbers rounded to the nearest ten.
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
50
60
300
8000
8000
2000
3000
8000
80
7000
8000
800
90
A
50
40
80
8000
900
800
A
50
800
800
3000
8000
40
5000
8000
2000
8000
Round 49 to the nearest tenA
Round 262 to the nearest hundredR
Round 62 to the nearest tenG
Round 2,694 to the nearest thousandH
Round 6,646 to the nearest thousandM
Round 5,291 to the nearest thousandC
Round 42 to the nearest tenS
Round 94 to the nearest tenW
Round 780 to the nearest hundredT
Round 924 to the nearest hundredF
Round 78 to the nearest tenL
Round 2,380 to the nearest thousandN
Round 7,958 to the nearest thousandE
0/13 letters found
Clue 5
Division facts (1-12) — the last clue
We found a box of old trail maps left by the suspect. We must divide them into equal groups for our rescue team to inspect.
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
90 ÷ 10 = ?
2 ÷ 2 = ?
8 ÷ 4 = ?
48 ÷ 6 = ?
15 ÷ 5 = ?
77 ÷ 11 = ?
12 ÷ 3 = ?
72 ÷ 6 = ?
33 ÷ 3 = ?
60 ÷ 6 = ?
60 ÷ 12 = ?
Step 2 — cross out the sentence with each answer
1.The villain climbed the rope ladder, then spun a decoder ring.
2.The villain threw the grappling hook, then snapped a mini camera.
3.The villain threw the grappling hook, then pointed a laser pointer.
4.The villain walked up with suction boots, then blew a spy whistle.
5.The villain climbed the rope ladder, then pointed a laser pointer.
6.The villain walked up with suction boots, then pointed a laser pointer.
7.The villain threw the grappling hook, then spun a decoder ring.
8.The villain walked up with suction boots, then shined a flash light.
9.The villain slid down the zipline pulley, then shined a flash light.
10.The villain slid down the zipline pulley, then spun a decoder ring.
11.The villain jumped with the bungee cord, then snapped a mini camera.
12.The villain climbed the rope ladder, then shined a flash light.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Great Treehouse Mystery
Culprit: Kai (suction boots · laser pointer · left handed · green helmet · cheese sticks)
- Clue 1 (Addition): "THE RAIDER DOES NOT HAVE A SPY WHISTLE"199 + 229 = 428 (T) · 116 + 101 = 217 (O) · 307 + 468 = 775 (D) · 471 + 454 = 925 (N) · 357 + 522 = 879 (R) · 305 + 171 = 476 (S) · 618 + 316 = 934 (L) · 408 + 284 = 692 (E) · 189 + 222 = 411 (W) · 149 + 306 = 455 (H) · 224 + 255 = 479 (P) · 221 + 147 = 368 (V) · 309 + 241 = 550 (I) · 157 + 111 = 268 (Y) · 329 + 595 = 924 (A)
- Clue 2 (Place value): "THE RAIDER WRITES WITH THEIR LEFT HAND"What is the value of the 6 in 760? = 60 (T) · What is the value of the 8 in 38,462? = 8000 (E) · What is the value of the 2 in 1,926? = 20 (R) · What is the value of the 1 in 1,050? = 1000 (W) · What is the value of the 7 in 706? = 700 (I) · What is the value of the 3 in 13,111? = 3000 (D) · What is the value of the 9 in 194? = 90 (F) · What is the value of the 2 in 62,705? = 2000 (A) · What is the value of the 3 in 539? = 30 (L) · What is the value of the 8 in 834? = 800 (S) · What is the value of the 9 in 59,237? = 9000 (H) · What is the value of the 5 in 5,821? = 5000 (N)
- Clue 3 (Skip counting): "WE FOUND CHEESE STICK WRAPPERS THERE"Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12 = 8 (W) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, ___, 33, 36 = 30 (S) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, ___, 55, 60 = 50 (A) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45 = 35 (H) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130 = 110 (I) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55 = 45 (R) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150 = 130 (E) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, ___, 21, 24 = 18 (D) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, ___, 14, 16 = 12 (N) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120 = 100 (K) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75 = 65 (O) · Skip-count by 10s. Fill the blank: 10, 20, 30, ___, 50, 60 = 40 (P) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24 = 20 (U) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, ___, 75, 80 = 70 (T) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, ___, 18, 21 = 15 (F) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35 = 25 (C)
- Clue 4 (Rounding): "A GREEN HELMET WAS LEFT AT THE SCENE"Round 49 to the nearest ten = 50 (A) · Round 262 to the nearest hundred = 300 (R) · Round 62 to the nearest ten = 60 (G) · Round 2,694 to the nearest thousand = 3000 (H) · Round 6,646 to the nearest thousand = 7000 (M) · Round 5,291 to the nearest thousand = 5000 (C) · Round 42 to the nearest ten = 40 (S) · Round 94 to the nearest ten = 90 (W) · Round 780 to the nearest hundred = 800 (T) · Round 924 to the nearest hundred = 900 (F) · Round 78 to the nearest ten = 80 (L) · Round 2,380 to the nearest thousand = 2000 (N) · Round 7,958 to the nearest thousand = 8000 (E)
- Clue 5 (Division facts (1-12)): surviving statement (box 6) → Kai90 ÷ 10 = 9 · 2 ÷ 2 = 1 · 8 ÷ 4 = 2 · 48 ÷ 6 = 8 · 15 ÷ 5 = 3 · 77 ÷ 11 = 7 · 12 ÷ 3 = 4 · 72 ÷ 6 = 12 · 33 ÷ 3 = 11 · 60 ÷ 6 = 10 · 60 ÷ 12 = 5
About this mystery
- Grade level
- Grade 3 math
- Math topics
- Addition, Place value, Skip counting, Rounding, Division
- Reading level
- grades 1-2
- Theme
- The Great Treehouse Mystery — set in The Great Oak Forest
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects