Grade 3Reading: grades 3-4Place valueAdditionSubtractionRoundingMissing addends

The Lost Compass Mystery

Someone snuck into the camp tent and took the golden compass! Work through the clues around the ruins to catch the thief.

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	Tool	Gear	Dominant Hand	Headwear	Weakness
Henry Drake	CAMP COMPASS	STEEL CROWBAR	RIGHT HANDED	BRIGHT HELMET	LOUD WHISTLE
Ruby Diaz	GRAPPLING HOOK	STEEL CROWBAR	RIGHT HANDED	BLACK HAT	LOUD WHISTLE
Zoe Adams	TORCH LIGHT	CLIMBING SPIKES	LEFT HANDED	RED BANDANA	LOUD WHISTLE
Jack Sterling	GRAPPLING HOOK	GLIDER WINGS	LEFT HANDED	BRIGHT HELMET	LOUD WHISTLE
Eli Vance	GRAPPLING HOOK	STEEL CROWBAR	RIGHT HANDED	RED BANDANA	NET TRAP
Ivy Morgan	CAMP COMPASS	ROPE LADDER	LEFT HANDED	BRIGHT HELMET	LOUD WHISTLE
Luke Harper	TORCH LIGHT	GLIDER WINGS	RIGHT HANDED	RED BANDANA	LOUD WHISTLE
Ella Vance	MAP SCROLL	ROPE LADDER	LEFT HANDED	BLACK HAT	NET TRAP
Ava Brooks	MAP SCROLL	STEEL CROWBAR	RIGHT HANDED	RED BANDANA	FLASH LIGHT
Toby Walsh	GRAPPLING HOOK	STEEL CROWBAR	LEFT HANDED	BLACK HAT	NET TRAP
Caleb Ross	GRAPPLING HOOK	POCKET TELESCOPE	RIGHT HANDED	BLACK HAT	NET TRAP
Owen Hayes	TORCH LIGHT	STEEL CROWBAR	LEFT HANDED	BLACK HAT	LOUD WHISTLE
Chloe Bennett	SMOKE BOMB	GLIDER WINGS	RIGHT HANDED	BRIGHT HELMET	NET TRAP
Sophia Bell	GRAPPLING HOOK	CLIMBING SPIKES	RIGHT HANDED	RED BANDANA	LOUD WHISTLE
Finn Connor	GRAPPLING HOOK	STEEL CROWBAR	LEFT HANDED	BRIGHT HELMET	NET TRAP
Grace Kim	GRAPPLING HOOK	GLIDER WINGS	LEFT HANDED	BLACK HAT	NET TRAP
Maya Santos	GRAPPLING HOOK	ROPE LADDER	LEFT HANDED	BLACK HAT	NET TRAP
Leo Rivera	TORCH LIGHT	GLIDER WINGS	LEFT HANDED	RED BANDANA	NET TRAP
Mason Cole	CAMP COMPASS	STEEL CROWBAR	LEFT HANDED	BLACK HAT	NET TRAP
Sam Patel	GRAPPLING HOOK	POCKET TELESCOPE	RIGHT HANDED	RED BANDANA	LOUD WHISTLE
Lily Price	TORCH LIGHT	STEEL CROWBAR	LEFT HANDED	BLACK HAT	NET TRAP

Clue 1

Place value

You inspect the locked tent keypad by checking the place value of each digit.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

5000

400

100

700

8000

700

800

4000

100

800

4000

5000

1000

100

8000

2000

4000

6000

100

8000

100

2000

What is the value of the 5 in 95,698?T

What is the value of the 8 in 283?V

What is the value of the 1 in 71,245?U

What is the value of the 8 in 809?N

What is the value of the 4 in 4,913?O

What is the value of the 7 in 1,702?I

What is the value of the 1 in 6,160?E

What is the value of the 4 in 246?L

What is the value of the 9 in 797?D

What is the value of the 4 in 6,475?H

What is the value of the 6 in 26,574?P

What is the value of the 2 in 2,450?R

What is the value of the 1 in 5,510?S

What is the value of the 8 in 38,159?A

0/14 letters found

Clue 2

Addition

You combine the supply totals recorded in the explorer notebook.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

258

463

524

411

556

411

614

524

684

258

581

411

298

524

552

258

463

814

959

668

524

668

90 + 168 =T

664 + 295 =N

334 + 222 =U

252 + 432 =C

184 + 114 =L

367 + 157 =E

126 + 285 =S

266 + 402 =D

357 + 257 =P

369 + 183 =F

349 + 465 =A

218 + 245 =H

182 + 399 =I

0/13 letters found

Clue 3

Subtraction

You figure out how many tools are missing by subtracting what remains.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

577

705

429

716

498

214

432

498

157

498

325

117

429

432

285

577

309

432

157

429

577

322

432

436

777 - 200 =T

1094 - 389 =H

427 - 213 =L

796 - 360 =P

1038 - 322 =V

322 - 165 =N

556 - 231 =S

434 - 317 =W

351 - 66 =K

650 - 218 =A

772 - 274 =I

642 - 213 =E

365 - 56 =O

686 - 364 =R

0/14 letters found

Clue 4

Rounding

The radio display only shows rounded numbers for the distance to camp.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

800

500

800

900

800

4000

2000

800

9000

500

400

4000

800

4000

400

9000

400

3000

400

Round 809 to the nearest hundredA

Round 3,043 to the nearest thousandN

Round 368 to the nearest hundredE

Round 9,363 to the nearest thousandS

Round 78 to the nearest tenF

Round 36 to the nearest tenH

Round 459 to the nearest hundredL

Round 93 to the nearest tenB

Round 2,393 to the nearest thousandW

Round 51 to the nearest tenC

Round 886 to the nearest hundredK

Round 4,376 to the nearest thousandT

0/12 letters found

Clue 5

Missing addends — the last clue

You solve the missing inventory numbers to find the final secret code.

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

1 + ___ = 8

4 + ___ = 6

7 + ___ = 12

7 + ___ = 8

9 + ___ = 15

2 + ___ = 6

7 + ___ = 16

1 + ___ = 11

4 + ___ = 16

2 + ___ = 13

8 + ___ = 11

Step 2 — cross out the sentence with each answer

1.The villain vanished using a smoke bomb, then pried open the lock with a steel crowbar.

2.The villain guided the way with a camp compass, then pried open the lock with a steel crowbar.

3.The villain checked the route on a map scroll, then scaled the cliff with climbing spikes.

4.The villain lit up the trail with a torch light, then scouted ahead with a pocket telescope.

5.The villain lit up the trail with a torch light, then pried open the lock with a steel crowbar.

6.The villain vanished using a smoke bomb, then escaped on glider wings.

7.The villain swung in with a grappling hook, then pried open the lock with a steel crowbar.

8.The villain swung in with a grappling hook, then escaped on glider wings.

9.The villain checked the route on a map scroll, then climbed down with a rope ladder.

10.The villain swung in with a grappling hook, then scaled the cliff with climbing spikes.

11.The villain checked the route on a map scroll, then scouted ahead with a pocket telescope.

12.The villain vanished using a smoke bomb, then scaled the cliff with climbing spikes.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Lost Compass Mystery

Culprit: Grace Kim (GRAPPLING HOOK · GLIDER WINGS · LEFT HANDED · BLACK HAT · NET TRAP)

Clue 1 (Place value): "THE VILLAIN DOES NOT USE A ROPE LADDER"
What is the value of the 5 in 95,698? = 5000 (T) · What is the value of the 8 in 283? = 80 (V) · What is the value of the 1 in 71,245? = 1000 (U) · What is the value of the 8 in 809? = 800 (N) · What is the value of the 4 in 4,913? = 4000 (O) · What is the value of the 7 in 1,702? = 700 (I) · What is the value of the 1 in 6,160? = 100 (E) · What is the value of the 4 in 246? = 40 (L) · What is the value of the 9 in 797? = 90 (D) · What is the value of the 4 in 6,475? = 400 (H) · What is the value of the 6 in 26,574? = 6000 (P) · What is the value of the 2 in 2,450? = 2000 (R) · What is the value of the 1 in 5,510? = 10 (S) · What is the value of the 8 in 38,159? = 8000 (A)
Clue 2 (Addition): "THE SUSPECT IS LEFT HANDED"
90 + 168 = 258 (T) · 664 + 295 = 959 (N) · 334 + 222 = 556 (U) · 252 + 432 = 684 (C) · 184 + 114 = 298 (L) · 367 + 157 = 524 (E) · 126 + 285 = 411 (S) · 266 + 402 = 668 (D) · 357 + 257 = 614 (P) · 369 + 183 = 552 (F) · 349 + 465 = 814 (A) · 218 + 245 = 463 (H) · 182 + 399 = 581 (I)
Clue 3 (Subtraction): "THE VILLAIN IS WEAK TO A NET TRAP"
777 - 200 = 577 (T) · 1094 - 389 = 705 (H) · 427 - 213 = 214 (L) · 796 - 360 = 436 (P) · 1038 - 322 = 716 (V) · 322 - 165 = 157 (N) · 556 - 231 = 325 (S) · 434 - 317 = 117 (W) · 351 - 66 = 285 (K) · 650 - 218 = 432 (A) · 772 - 274 = 498 (I) · 642 - 213 = 429 (E) · 365 - 56 = 309 (O) · 686 - 364 = 322 (R)
Clue 4 (Rounding): "A BLACK HAT WAS LEFT AT THE SCENE"
Round 809 to the nearest hundred = 800 (A) · Round 3,043 to the nearest thousand = 3000 (N) · Round 368 to the nearest hundred = 400 (E) · Round 9,363 to the nearest thousand = 9000 (S) · Round 78 to the nearest ten = 80 (F) · Round 36 to the nearest ten = 40 (H) · Round 459 to the nearest hundred = 500 (L) · Round 93 to the nearest ten = 90 (B) · Round 2,393 to the nearest thousand = 2000 (W) · Round 51 to the nearest ten = 50 (C) · Round 886 to the nearest hundred = 900 (K) · Round 4,376 to the nearest thousand = 4000 (T)
Clue 5 (Missing addends): surviving statement (box 8) → Grace Kim
1 + ___ = 8 = 7 · 4 + ___ = 6 = 2 · 7 + ___ = 12 = 5 · 7 + ___ = 8 = 1 · 9 + ___ = 15 = 6 · 2 + ___ = 6 = 4 · 7 + ___ = 16 = 9 · 1 + ___ = 11 = 10 · 4 + ___ = 16 = 12 · 2 + ___ = 13 = 11 · 8 + ___ = 11 = 3

About this mystery

Grade level: Grade 3 math
Math topics: Place value, Addition, Subtraction, Rounding, Missing addends
Reading level: grades 3-4
Theme: The Lost Compass Mystery — set in Mist Island Jungle Ruins
Format: Interactive online & printable worksheet with answer key
Solution: One unique, verified culprit among 21 suspects

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