Grade 4Reading: grades 3-4RoundingPlace valueAdditionSubtractionDivision
The Mystery of the Sunken Compass
Someone sneaked into the main lodge and swiped the golden camp compass! The Treehouse Club needs to search the camp, gather evidence, and figure out who took it before the evening campfire.
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 | Main Gear | Extra Tool | Dominant Hand | Headwear | Camp Trap |
|---|---|---|---|---|---|
| Ethan Price | Jet Shoes | Waterproof Pouch | Left-handed | Blue Cap | Loud Whistle |
| Chloe Diaz | Scuba Gear | Waterproof Pouch | Right-handed | Red Bandana | Loud Whistle |
| Lily Ward | Rope Ladder | Whistle Band | Right-handed | Red Bandana | Bright Flashlight |
| Jack Hayes | Rope Ladder | Whistle Band | Left-handed | Red Bandana | Pine Sap |
| Ruby Kim | Grappling Hook | Waterproof Pouch | Left-handed | Red Bandana | Bright Flashlight |
| Ava Ross | Grappling Hook | Whistle Band | Left-handed | Green Visor | Loud Whistle |
| Grace Hill | Scuba Gear | Whistle Band | Left-handed | Red Bandana | Bright Flashlight |
| Finn Morgan | Rope Ladder | Night Visor | Right-handed | Green Visor | Loud Whistle |
| Mia Chang | Rope Ladder | Flash Beacon | Right-handed | Green Visor | Bright Flashlight |
| Nora Patel | Jet Shoes | Flash Beacon | Left-handed | Red Bandana | Bright Flashlight |
| Sam Rivera | Glider Wings | Waterproof Pouch | Left-handed | Red Bandana | Loud Whistle |
| Toby Walsh | Rope Ladder | Waterproof Pouch | Left-handed | Green Visor | Bright Flashlight |
| Ella Cole | Jet Shoes | Walkie Talkie | Right-handed | Blue Cap | Bright Flashlight |
| Maya Cruz | Rope Ladder | Night Visor | Left-handed | Red Bandana | Bright Flashlight |
| Eli Brooks | Scuba Gear | Night Visor | Left-handed | Red Bandana | Bright Flashlight |
| Caleb Stone | Jet Shoes | Walkie Talkie | Left-handed | Green Visor | Pine Sap |
| Zoe Chen | Scuba Gear | Walkie Talkie | Right-handed | Green Visor | Bright Flashlight |
| Owen Drake | Jet Shoes | Whistle Band | Right-handed | Red Bandana | Bright Flashlight |
| Leo Vance | Glider Wings | Waterproof Pouch | Right-handed | Red Bandana | Pine Sap |
| Mason Ellis | Jet Shoes | Whistle Band | Left-handed | Blue Cap | Pine Sap |
| Max Bennett | Glider Wings | Walkie Talkie | Left-handed | Blue Cap | Bright Flashlight |
Clue 1
Rounding
The lookout scanner display shows estimated distances rounded to the nearest ten. Round the numbers to reveal the first piece of evidence.
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
1100
30
9000
1700
50
90
90
290
50
2300
7000
20
9000
230
2300
20
T
1100
4300
230
9000
290
2900
290
T
1100
9000
5000
300
5000
20
20
430
300
20
4300
3000
30
Round 1,112 to the nearest hundredT
Round 54 to the nearest tenI
Round 2,304 to the nearest hundredN
Round 2,503 to the nearest thousandC
Round 7,375 to the nearest thousandD
Round 426 to the nearest tenF
Round 33 to the nearest tenH
Round 5,437 to the nearest thousandR
Round 19 to the nearest tenO
Round 294 to the nearest tenA
Round 1,651 to the nearest hundredV
Round 2,903 to the nearest hundredW
Round 233 to the nearest tenS
Round 280 to the nearest hundredP
Round 8,644 to the nearest thousandE
Round 4,318 to the nearest hundredU
Round 91 to the nearest tenL
0/17 letters found
Clue 2
Place value
The locked trailbox needs a code built from place values. Check the value of each digit to open the latch.
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
5000
70
400
T
5000
70
200
400
300
50
400
300
T
5000
10
30
200
600
T
5000
9000
300
30
60
900
3000
50
400
300
T
5000
70
3000
600
500
What is the value of the 5 in 5,927?T
What is the value of the 1 in 715?P
What is the value of the 3 in 3,828?A
What is the value of the 3 in 7,376?F
What is the value of the 5 in 8,589?D
What is the value of the 7 in 2,076?H
What is the value of the 3 in 236?R
What is the value of the 4 in 3,411?E
What is the value of the 9 in 922?M
What is the value of the 6 in 655?N
What is the value of the 5 in 9,853?L
What is the value of the 6 in 3,261?O
What is the value of the 2 in 217?I
What is the value of the 9 in 29,758?S
0/14 letters found
Clue 3
Addition
The detectives tallied footmarks along the muddy shore. Add the numbers to trace the trail.
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
3779
3498
9020
T
3779
3498
2626
9020
4041
5231
3653
4090
9849
2046
2626
9544
8678
9020
8678
9849
9505
3653
9849
4824
2626
6369
3498
T
3779
4041
2046
3653
4090
3498
2046
2626
6369
3498
T
3779
2371 + 1408 =T
6360 + 3489 =B
2504 + 1586 =S
1735 + 3089 =R
5865 + 3679 =N
3228 + 5450 =D
2236 + 2995 =W
2276 + 1377 =A
1318 + 1308 =I
5345 + 3675 =E
4773 + 4732 =Y
2735 + 1306 =F
3596 + 2773 =G
1687 + 1811 =H
1242 + 804 =L
0/15 letters found
Clue 4
Subtraction
Comparing supply lists before and after the raid shows what went missing. Subtract the amounts to crack the clue.
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
8742
2919
3437
4107
3793
A
8742
3762
4107
A
8742
3762
A
8742
3983
A
8742
7199
4107
2919
2768
5448
5448
3437
4107
3762
3437
A
8742
2919
7523
6933
3437
2228
A
8742
3793
1513
3762
12051 - 3309 =A
3297 - 1069 =C
7800 - 601 =S
6456 - 2473 =W
3979 - 1211 =O
5644 - 2207 =E
5574 - 4061 =I
11703 - 4180 =T
5640 - 1878 =N
7462 - 3355 =D
7239 - 4320 =R
4449 - 656 =B
7044 - 111 =H
9459 - 4011 =P
0/14 letters found
Clue 5
Division facts (1-12) — the last clue
The search area is divided into equal sections for the team. Divide the total grid to discover the final clue.
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
6 ÷ 6 = ?
24 ÷ 8 = ?
44 ÷ 4 = ?
28 ÷ 7 = ?
70 ÷ 10 = ?
48 ÷ 6 = ?
24 ÷ 12 = ?
40 ÷ 8 = ?
48 ÷ 8 = ?
9 ÷ 1 = ?
10 ÷ 1 = ?
Step 2 — cross out the sentence with each answer
1.The villain dived under the dock with scuba gear, then scouted ahead with a night visor.
2.The villain swung across the creek with a grappling hook, then tucked the loot into a waterproof pouch.
3.The villain dived under the dock with scuba gear, then blew a sharp signal on a whistle band.
4.The villain climbed the high wall with a rope ladder, then blew a sharp signal on a whistle band.
5.The villain swung across the creek with a grappling hook, then scouted ahead with a night visor.
6.The villain swung across the creek with a grappling hook, then chattered into a secret walkie talkie.
7.The villain zoomed up the path with jet shoes, then scouted ahead with a night visor.
8.The villain zoomed up the path with jet shoes, then tucked the loot into a waterproof pouch.
9.The villain zoomed up the path with jet shoes, then blew a sharp signal on a whistle band.
10.The villain climbed the high wall with a rope ladder, then chattered into a secret walkie talkie.
11.The villain climbed the high wall with a rope ladder, then scouted ahead with a night visor.
12.The villain zoomed up the path with jet shoes, then signaled a partner using a flash beacon.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Mystery of the Sunken Compass
Culprit: Nora Patel (Jet Shoes · Flash Beacon · Left-handed · Red Bandana · Bright Flashlight)
- Clue 1 (Rounding): "THE VILLAIN DOES NOT USE A WATERPROOF POUCH"Round 1,112 to the nearest hundred = 1100 (T) · Round 54 to the nearest ten = 50 (I) · Round 2,304 to the nearest hundred = 2300 (N) · Round 2,503 to the nearest thousand = 3000 (C) · Round 7,375 to the nearest thousand = 7000 (D) · Round 426 to the nearest ten = 430 (F) · Round 33 to the nearest ten = 30 (H) · Round 5,437 to the nearest thousand = 5000 (R) · Round 19 to the nearest ten = 20 (O) · Round 294 to the nearest ten = 290 (A) · Round 1,651 to the nearest hundred = 1700 (V) · Round 2,903 to the nearest hundred = 2900 (W) · Round 233 to the nearest ten = 230 (S) · Round 280 to the nearest hundred = 300 (P) · Round 8,644 to the nearest thousand = 9000 (E) · Round 4,318 to the nearest hundred = 4300 (U) · Round 91 to the nearest ten = 90 (L)
- Clue 2 (Place value): "THE THIEF LEFT PRINTS FROM A LEFT HAND"What is the value of the 5 in 5,927? = 5000 (T) · What is the value of the 1 in 715? = 10 (P) · What is the value of the 3 in 3,828? = 3000 (A) · What is the value of the 3 in 7,376? = 300 (F) · What is the value of the 5 in 8,589? = 500 (D) · What is the value of the 7 in 2,076? = 70 (H) · What is the value of the 3 in 236? = 30 (R) · What is the value of the 4 in 3,411? = 400 (E) · What is the value of the 9 in 922? = 900 (M) · What is the value of the 6 in 655? = 600 (N) · What is the value of the 5 in 9,853? = 50 (L) · What is the value of the 6 in 3,261? = 60 (O) · What is the value of the 2 in 217? = 200 (I) · What is the value of the 9 in 29,758? = 9000 (S)
- Clue 3 (Addition): "THE THIEF WAS BLINDED BY A BRIGHT FLASHLIGHT"2371 + 1408 = 3779 (T) · 6360 + 3489 = 9849 (B) · 2504 + 1586 = 4090 (S) · 1735 + 3089 = 4824 (R) · 5865 + 3679 = 9544 (N) · 3228 + 5450 = 8678 (D) · 2236 + 2995 = 5231 (W) · 2276 + 1377 = 3653 (A) · 1318 + 1308 = 2626 (I) · 5345 + 3675 = 9020 (E) · 4773 + 4732 = 9505 (Y) · 2735 + 1306 = 4041 (F) · 3596 + 2773 = 6369 (G) · 1687 + 1811 = 3498 (H) · 1242 + 804 = 2046 (L)
- Clue 4 (Subtraction): "A RED BANDANA WAS DROPPED NEAR THE CABIN"12051 - 3309 = 8742 (A) · 3297 - 1069 = 2228 (C) · 7800 - 601 = 7199 (S) · 6456 - 2473 = 3983 (W) · 3979 - 1211 = 2768 (O) · 5644 - 2207 = 3437 (E) · 5574 - 4061 = 1513 (I) · 11703 - 4180 = 7523 (T) · 5640 - 1878 = 3762 (N) · 7462 - 3355 = 4107 (D) · 7239 - 4320 = 2919 (R) · 4449 - 656 = 3793 (B) · 7044 - 111 = 6933 (H) · 9459 - 4011 = 5448 (P)
- Clue 5 (Division facts (1-12)): surviving statement (box 12) → Nora Patel6 ÷ 6 = 1 · 24 ÷ 8 = 3 · 44 ÷ 4 = 11 · 28 ÷ 7 = 4 · 70 ÷ 10 = 7 · 48 ÷ 6 = 8 · 24 ÷ 12 = 2 · 40 ÷ 8 = 5 · 48 ÷ 8 = 6 · 9 ÷ 1 = 9 · 10 ÷ 1 = 10
About this mystery
- Grade level
- Grade 4 math
- Math topics
- Rounding, Place value, Addition, Subtraction, Division
- Reading level
- grades 3-4
- Theme
- The Mystery of the Sunken Compass — set in Crabapple Island Adventure Camp
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects