Grade 4Reading: grades 3-4Fractions of a numberRoundingAdditionSubtraction

The Skyship Compass Mystery

Someone snuck into the navigation tower at Skyship Harbor and swapped the Golden Compass with a fake bronze gear. Chief Navigator Barnaby needs the Sky Cadets to solve the clues, clear innocent suspects, and catch the sneaky sky bandit before the fleet sets sail.

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	Gear Pack	Gadget Tool	Dominant Hand	Hair Style	Vulnerability
Officer Ruby	Steam Grapple	Pocket Radar	Left Handed	Spiky Blue	Sticky Honey
Rigger Mia	Wind Whistle	Laser Goggles	Left Handed	Braided Red	Bright Flash
Lookout Ava	Steam Grapple	Pocket Radar	Right Handed	Spiky Blue	Bright Flash
Sailor Ella	Glider Wings	Laser Goggles	Left Handed	Curly Silver	Loud Whistles
Rigger Toby	Cloud Anchor	Pocket Radar	Left Handed	Spiky Blue	Loud Whistles
Sky Sailor Ivy	Glider Wings	Spyglass Lens	Left Handed	Braided Red	Bright Flash
Captain Arthur	Cloud Anchor	Map Compass	Left Handed	Spiky Blue	Bright Flash
Scout Liam	Cloud Anchor	Laser Goggles	Left Handed	Spiky Blue	Bright Flash
Rigger Mason	Brass Jetpack	Signal Flare	Left Handed	Spiky Blue	Bright Flash
Lookout Owen	Wind Whistle	Signal Flare	Right Handed	Braided Red	Sticky Honey
Captain Felix	Steam Grapple	Signal Flare	Left Handed	Spiky Blue	Sticky Honey
Cadet Maya	Steam Grapple	Laser Goggles	Right Handed	Curly Silver	Loud Whistles
Officer Eli	Steam Grapple	Laser Goggles	Left Handed	Curly Silver	Loud Whistles
Engineer Ben	Cloud Anchor	Map Compass	Left Handed	Braided Red	Bright Flash
Flyer Chloe	Steam Grapple	Spyglass Lens	Left Handed	Curly Silver	Bright Flash
Navigator Nora	Steam Grapple	Map Compass	Left Handed	Spiky Blue	Bright Flash
Navigator Ethan	Wind Whistle	Pocket Radar	Left Handed	Spiky Blue	Sticky Honey
Pilot Hazel	Cloud Anchor	Signal Flare	Right Handed	Spiky Blue	Loud Whistles
Pilot Caleb	Glider Wings	Signal Flare	Left Handed	Curly Silver	Bright Flash
Engineer Zoe	Glider Wings	Map Compass	Left Handed	Spiky Blue	Bright Flash
Deckhand Penny	Brass Jetpack	Signal Flare	Left Handed	Braided Red	Sticky Honey

Clue 1

Fractions of a number

Barnaby counted the fuel canisters left on the dock and realized only a fraction held secret notes.

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

1/4 of 52 =T

2/4 of 12 =U

3/6 of 68 =G

6/8 of 36 =A

3/10 of 130 =N

5/10 of 60 =F

1/2 of 14 =O

2/6 of 15 =L

2/10 of 185 =V

2/8 of 8 =H

1/5 of 85 =I

2/4 of 32 =E

5/10 of 76 =R

1/4 of 32 =D

3/6 of 24 =S

0/15 letters found

Clue 2

Rounding

The flight altimeter display only shows rounded numbers when tracking mysterious flying shadows.

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

290

1100

200

5000

1700

130

290

200

3000

1700

1300

290

430

1100

200

1700

290

1100

200

3000

200

3000

1700

1100

430

110

1700

2300

200

3000

130

5000

230

Round 286 to the nearest tenW

Round 243 to the nearest hundredT

Round 126 to the nearest tenA

Round 1,253 to the nearest hundredM

Round 226 to the nearest tenD

Round 106 to the nearest tenL

Round 2,282 to the nearest hundredF

Round 4,989 to the nearest thousandN

Round 1,728 to the nearest hundredE

Round 2,893 to the nearest thousandH

Round 1,060 to the nearest hundredI

Round 427 to the nearest tenR

Round 16 to the nearest tenS

0/13 letters found

Clue 3

Addition

The deckhands gathered up all the brass gears dropped along the runway to figure out 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.

9131

3726

4750

6139

9662

7552

5718

9662

3173

2379

3726

9662

4750

7552

8673

4750

8673

4750

6590

4750

2379

6554

9698

4364

8988

5762

9698

9662

6942

3726

9131

6554

7552

5718

2379

3726

5713 + 3418 =T

3580 + 2559 =V

4920 + 2632 =L

3657 + 5331 =M

2886 + 2832 =A

2174 + 999 =N

1469 + 2895 =O

2617 + 4325 =G

748 + 1631 =S

3464 + 6198 =I

5994 + 2679 =D

2379 + 4175 =F

2338 + 1388 =H

3422 + 6276 =R

2530 + 4060 =Y

3149 + 2613 =B

1521 + 3229 =E

0/17 letters found

Clue 4

Subtraction

After clearing out the duplicate supply boxes, the crew calculated how many crates remained missing.

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

1244

4248

8190

6089

3830

8372

3566

4248

1244

3351

1315

5886

5998

3566

1262

8190

6071

5589

3827

2997

3351

3830

6725

5998

8190

8372

5998

5789

3566

6089

3830

1315

3830

2928 - 1684 =O

9469 - 3398 =K

5853 - 4591 =P

9533 - 3744 =T

10061 - 4175 =D

6708 - 2878 =E

8285 - 2196 =C

5871 - 2305 =S

6394 - 396 =A

10999 - 2627 =R

3974 - 623 =U

3964 - 137 =B

4777 - 529 =F

8010 - 1285 =H

11258 - 3068 =I

9970 - 4381 =Y

3223 - 1908 =N

3852 - 855 =L

0/18 letters found

Clue 5

Fractions of a number — the last clue

Barnaby examined the sky charts and calculated what fraction of the air routes were still safe.

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

2/8 of 20 = ?

1/4 of 36 = ?

2/10 of 10 = ?

2/3 of 6 = ?

2/6 of 33 = ?

1/8 of 24 = ?

1/3 of 21 = ?

1/4 of 32 = ?

1/3 of 3 = ?

4/10 of 15 = ?

4/6 of 15 = ?

Step 2 — cross out the sentence with each answer

1.The villain fired a steam grapple onto the ledge, then tracked the fleet with a pocket radar.

2.The villain fired a steam grapple onto the ledge, then checked directions on a map compass.

3.The villain zoomed past on a brass jetpack, then tracked the fleet with a pocket radar.

4.The villain dropped a cloud anchor into the mist, then lit up the night with a signal flare.

5.The villain dropped a cloud anchor into the mist, then checked directions on a map compass.

6.The villain zoomed past on a brass jetpack, then scanned the sky with laser goggles.

7.The villain zoomed past on a brass jetpack, then lit up the night with a signal flare.

8.The villain zoomed past on a brass jetpack, then adjusted a sharp spyglass lens.

9.The villain soared overhead using glider wings, then checked directions on a map compass.

10.The villain blew a wind whistle to clear the deck, then tracked the fleet with a pocket radar.

11.The villain zoomed past on a brass jetpack, then checked directions on a map compass.

12.The villain dropped a cloud anchor into the mist, then scanned the sky with laser goggles.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Skyship Compass Mystery

Culprit: Scout Liam (Cloud Anchor · Laser Goggles · Left Handed · Spiky Blue · Bright Flash)

Clue 1 (Fractions of a number): "THE VILLAIN DOES NOT USE A SIGNAL FLARE"
1/4 of 52 = 13 (T) · 2/4 of 12 = 6 (U) · 3/6 of 68 = 34 (G) · 6/8 of 36 = 27 (A) · 3/10 of 130 = 39 (N) · 5/10 of 60 = 30 (F) · 1/2 of 14 = 7 (O) · 2/6 of 15 = 5 (L) · 2/10 of 185 = 37 (V) · 2/8 of 8 = 2 (H) · 1/5 of 85 = 17 (I) · 2/4 of 32 = 16 (E) · 5/10 of 76 = 38 (R) · 1/4 of 32 = 8 (D) · 3/6 of 24 = 12 (S)
Clue 2 (Rounding): "WITNESS SAW THEM WRITE WITH THEIR LEFT HAND"
Round 286 to the nearest ten = 290 (W) · Round 243 to the nearest hundred = 200 (T) · Round 126 to the nearest ten = 130 (A) · Round 1,253 to the nearest hundred = 1300 (M) · Round 226 to the nearest ten = 230 (D) · Round 106 to the nearest ten = 110 (L) · Round 2,282 to the nearest hundred = 2300 (F) · Round 4,989 to the nearest thousand = 5000 (N) · Round 1,728 to the nearest hundred = 1700 (E) · Round 2,893 to the nearest thousand = 3000 (H) · Round 1,060 to the nearest hundred = 1100 (I) · Round 427 to the nearest ten = 430 (R) · Round 16 to the nearest ten = 20 (S)
Clue 3 (Addition): "THE VILLAIN SHIELDED EYES FROM BRIGHT FLASH"
5713 + 3418 = 9131 (T) · 3580 + 2559 = 6139 (V) · 4920 + 2632 = 7552 (L) · 3657 + 5331 = 8988 (M) · 2886 + 2832 = 5718 (A) · 2174 + 999 = 3173 (N) · 1469 + 2895 = 4364 (O) · 2617 + 4325 = 6942 (G) · 748 + 1631 = 2379 (S) · 3464 + 6198 = 9662 (I) · 5994 + 2679 = 8673 (D) · 2379 + 4175 = 6554 (F) · 2338 + 1388 = 3726 (H) · 3422 + 6276 = 9698 (R) · 2530 + 4060 = 6590 (Y) · 3149 + 2613 = 5762 (B) · 1521 + 3229 = 4750 (E)
Clue 4 (Subtraction): "OFFICERS FOUND A SPIKY BLUE HAIR AT SCENE"
2928 - 1684 = 1244 (O) · 9469 - 3398 = 6071 (K) · 5853 - 4591 = 1262 (P) · 9533 - 3744 = 5789 (T) · 10061 - 4175 = 5886 (D) · 6708 - 2878 = 3830 (E) · 8285 - 2196 = 6089 (C) · 5871 - 2305 = 3566 (S) · 6394 - 396 = 5998 (A) · 10999 - 2627 = 8372 (R) · 3974 - 623 = 3351 (U) · 3964 - 137 = 3827 (B) · 4777 - 529 = 4248 (F) · 8010 - 1285 = 6725 (H) · 11258 - 3068 = 8190 (I) · 9970 - 4381 = 5589 (Y) · 3223 - 1908 = 1315 (N) · 3852 - 855 = 2997 (L)
Clue 5 (Fractions of a number): surviving statement (box 12) → Scout Liam
2/8 of 20 = 5 · 1/4 of 36 = 9 · 2/10 of 10 = 2 · 2/3 of 6 = 4 · 2/6 of 33 = 11 · 1/8 of 24 = 3 · 1/3 of 21 = 7 · 1/4 of 32 = 8 · 1/3 of 3 = 1 · 4/10 of 15 = 6 · 4/6 of 15 = 10

About this mystery

Grade level: Grade 4 math
Math topics: Fractions of a number, Rounding, Addition, Subtraction
Reading level: grades 3-4
Theme: The Skyship Compass Mystery — set in Skyship Harbor
Format: Interactive online & printable worksheet with answer key
Solution: One unique, verified culprit among 21 suspects

More free printable math cases

4th grade worksheets Addition worksheets Subtraction worksheets Rounding worksheets Fractions of a number worksheets 🏴‍☠️ Pirates worksheets All worksheets →

The Mystery of Jaguar Isle

Grade 4

The Great Gridiron Trophy Heist

Grade 4

The Mystery of the Missing Gold Football

Grade 4

The Great Championship Trophy Caper

Grade 4