Grade 4Reading: grades 3-4RoundingAdditionSubtractionMultiplicationDivision
The Lost Island Crystal Heist
The legendary Sun Crystal vanished from the main expedition tent right before sunrise! Use your detective skills to catch the sneaky rogue before they escape the island.
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 Gadget | Loot Stolen | Accessory | Hairstyle | Phobia |
|---|---|---|---|---|---|
| Indy Drake | grapple hook | bronze key | wears eye patch | braided blond hair | scared of snakes |
| Zack Brooks | grapple hook | brass compass | wears eye patch | braided blond hair | scared of snakes |
| Nora Hayes | smoke bomb | map scroll | wears eye patch | braided blond hair | scared of snakes |
| Bruno Steele | jet glider | gold coin | wears eye patch | braided blond hair | scared of snakes |
| Rosa Blair | jet glider | spyglass | wears goggles | spiked brown hair | scared of frogs |
| Ruby Sterling | jet glider | spyglass | wears goggles | braided blond hair | scared of snakes |
| Clara Finch | jet glider | brass compass | wears eye patch | braided blond hair | scared of frogs |
| Axel Thorne | jet glider | map scroll | wears eye patch | slicked black hair | scared of bats |
| Hank Forest | grapple hook | gold coin | wears goggles | slicked black hair | scared of bats |
| Nina Vega | smoke bomb | gold coin | wears eye patch | spiked brown hair | scared of snakes |
| Piper Flint | jet glider | gold coin | wears goggles | spiked brown hair | scared of frogs |
| Dax Rivera | zipline | bronze key | wears goggles | spiked brown hair | scared of snakes |
| Maya Ranger | grapple hook | brass compass | wears eye patch | spiked brown hair | scared of snakes |
| Rex Turner | zipline | bronze key | wears eye patch | braided blond hair | scared of frogs |
| Cole Hunter | compass blast | brass compass | wears eye patch | spiked brown hair | scared of snakes |
| Cora Wilde | jet glider | spyglass | wears goggles | spiked brown hair | scared of bats |
| Tess Morgan | compass blast | map scroll | wears eye patch | braided blond hair | scared of snakes |
| Ivy Cross | compass blast | gold coin | wears goggles | spiked brown hair | scared of snakes |
| Sam Croft | jet glider | map scroll | wears goggles | slicked black hair | scared of frogs |
| Flynn West | compass blast | gold coin | wears eye patch | braided blond hair | scared of frogs |
| Owen Marsh | zipline | gold coin | wears goggles | braided blond hair | scared of bats |
Clue 1
Rounding
The digital altitude gauge on the radar board rounded the airship height to give us our first 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.
T
290
30
1300
1100
900
1300
7000
20
200
3700
50
230
90
300
700
T
290
130
700
130
900
3000
T
290
50
1100
1300
7000
430
300
3000
900
70
1300
20
1300
200
Round 291 to the nearest tenT
Round 29 to the nearest tenH
Round 24 to the nearest tenK
Round 6,870 to the nearest thousandA
Round 72 to the nearest tenZ
Round 3,687 to the nearest hundredC
Round 1,272 to the nearest hundredE
Round 433 to the nearest tenB
Round 48 to the nearest tenU
Round 910 to the nearest hundredN
Round 2,800 to the nearest thousandO
Round 1,107 to the nearest hundredS
Round 226 to the nearest tenL
Round 309 to the nearest hundredR
Round 92 to the nearest tenP
Round 155 to the nearest hundredY
Round 674 to the nearest hundredI
Round 130 to the nearest tenD
0/18 letters found
Clue 2
Addition
We tallied all the supply crates packed in the cargo tent to reveal the second 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
2553
9404
5590
3048
5760
8175
7489
7489
7489
A
2553
9404
3048
6361
8175
3328
5590
3645
3645
A
2553
5590
5760
9404
8175
A
2553
4967
A
2553
5760
8175
4059
8175
5770
A
2553
3048
8367
6361
1145 + 1408 =A
3073 + 6331 =W
2644 + 5531 =E
1129 + 2516 =L
2982 + 1985 =R
1435 + 1893 =V
2396 + 3364 =N
5616 + 2751 =C
3952 + 3537 =S
1142 + 1906 =T
3256 + 2514 =P
2479 + 1580 =Y
1948 + 4413 =H
3365 + 2225 =I
0/14 letters found
Clue 3
Subtraction
Comparing the remaining trail rations against what was taken helped unlock the third 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.
T
4646
5483
8851
5129
6050
5835
5122
8851
5129
4617
4033
8851
5122
6050
4617
T
4646
8851
5129
3022
1550
7309
T
4646
T
4646
5835
4788
8650
6050
3022
4788
6050
2401
8851
5859 - 1213 =T
5161 - 373 =N
7751 - 2622 =R
8952 - 101 =E
7570 - 261 =O
4731 - 1709 =S
6406 - 571 =I
3440 - 1039 =K
3217 - 1667 =P
6887 - 2270 =F
7442 - 3409 =L
8842 - 3720 =D
7556 - 1506 =A
8069 - 2586 =H
8824 - 174 =G
0/15 letters found
Clue 4
Multiplication facts (1-12)
Counting equal rows of tents across the campsite uncovered our fourth 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.
B
55
99
90
48
1
28
1
B
55
24
49
2
1
36
90
48
99
22
90
6
1
99
49
54
54
28
1
90
64
64
36
28
6
11
28
2
28
11 × 5 =B
2 × 1 =N
2 × 11 =W
1 × 1 =D
3 × 8 =L
3 × 12 =H
4 × 7 =E
9 × 10 =A
3 × 2 =S
9 × 11 =R
6 × 9 =P
7 × 7 =O
8 × 6 =I
8 × 8 =T
11 × 1 =C
0/15 letters found
Clue 5
Division facts (1-12) — the last clue
Sharing the search maps equally among the rescue squads led us straight to 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
15 ÷ 5 = ?
90 ÷ 9 = ?
84 ÷ 7 = ?
88 ÷ 8 = ?
36 ÷ 9 = ?
56 ÷ 8 = ?
96 ÷ 12 = ?
45 ÷ 9 = ?
6 ÷ 1 = ?
90 ÷ 10 = ?
1 ÷ 1 = ?
Step 2 — cross out the sentence with each answer
1.The villain slid across on a long zipline, then stole the ancient map scroll.
2.The villain knocked guards back with a compass blast, then stole the ancient map scroll.
3.The villain threw down a thick smoke bomb, then stole the ancient map scroll.
4.The villain swung in with a grapple hook, then grabbed the heavy gold coin.
5.The villain swung in with a grapple hook, then stole the ancient map scroll.
6.The villain zoomed past on a jet glider, then snatched the brass spyglass.
7.The villain knocked guards back with a compass blast, then swiped the shiny bronze key.
8.The villain zoomed past on a jet glider, then stole the ancient map scroll.
9.The villain swung in with a grapple hook, then snatched the brass spyglass.
10.The villain swung in with a grapple hook, then pocketed the antique brass compass.
11.The villain threw down a thick smoke bomb, then grabbed the heavy gold coin.
12.The villain zoomed past on a jet glider, then grabbed the heavy gold coin.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Lost Island Crystal Heist
Culprit: Tess Morgan (compass blast · map scroll · wears eye patch · braided blond hair · scared of snakes)
- Clue 1 (Rounding): "THE SNEAKY CULPRIT DID NOT USE A BRONZE KEY"Round 291 to the nearest ten = 290 (T) · Round 29 to the nearest ten = 30 (H) · Round 24 to the nearest ten = 20 (K) · Round 6,870 to the nearest thousand = 7000 (A) · Round 72 to the nearest ten = 70 (Z) · Round 3,687 to the nearest hundred = 3700 (C) · Round 1,272 to the nearest hundred = 1300 (E) · Round 433 to the nearest ten = 430 (B) · Round 48 to the nearest ten = 50 (U) · Round 910 to the nearest hundred = 900 (N) · Round 2,800 to the nearest thousand = 3000 (O) · Round 1,107 to the nearest hundred = 1100 (S) · Round 226 to the nearest ten = 230 (L) · Round 309 to the nearest hundred = 300 (R) · Round 92 to the nearest ten = 90 (P) · Round 155 to the nearest hundred = 200 (Y) · Round 674 to the nearest hundred = 700 (I) · Round 130 to the nearest ten = 130 (D)
- Clue 2 (Addition): "A WITNESS SAW THE VILLAIN WEAR AN EYE PATCH"1145 + 1408 = 2553 (A) · 3073 + 6331 = 9404 (W) · 2644 + 5531 = 8175 (E) · 1129 + 2516 = 3645 (L) · 2982 + 1985 = 4967 (R) · 1435 + 1893 = 3328 (V) · 2396 + 3364 = 5760 (N) · 5616 + 2751 = 8367 (C) · 3952 + 3537 = 7489 (S) · 1142 + 1906 = 3048 (T) · 3256 + 2514 = 5770 (P) · 2479 + 1580 = 4059 (Y) · 1948 + 4413 = 6361 (H) · 3365 + 2225 = 5590 (I)
- Clue 3 (Subtraction): "THE RAIDER FLED AFTER SPOTTING A SNAKE"5859 - 1213 = 4646 (T) · 5161 - 373 = 4788 (N) · 7751 - 2622 = 5129 (R) · 8952 - 101 = 8851 (E) · 7570 - 261 = 7309 (O) · 4731 - 1709 = 3022 (S) · 6406 - 571 = 5835 (I) · 3440 - 1039 = 2401 (K) · 3217 - 1667 = 1550 (P) · 6887 - 2270 = 4617 (F) · 7442 - 3409 = 4033 (L) · 8842 - 3720 = 5122 (D) · 7556 - 1506 = 6050 (A) · 8069 - 2586 = 5483 (H) · 8824 - 174 = 8650 (G)
- Clue 4 (Multiplication facts (1-12)): "BRAIDED BLOND HAIR WAS DROPPED AT THE SCENE"11 × 5 = 55 (B) · 2 × 1 = 2 (N) · 2 × 11 = 22 (W) · 1 × 1 = 1 (D) · 3 × 8 = 24 (L) · 3 × 12 = 36 (H) · 4 × 7 = 28 (E) · 9 × 10 = 90 (A) · 3 × 2 = 6 (S) · 9 × 11 = 99 (R) · 6 × 9 = 54 (P) · 7 × 7 = 49 (O) · 8 × 6 = 48 (I) · 8 × 8 = 64 (T) · 11 × 1 = 11 (C)
- Clue 5 (Division facts (1-12)): surviving statement (box 2) → Tess Morgan15 ÷ 5 = 3 · 90 ÷ 9 = 10 · 84 ÷ 7 = 12 · 88 ÷ 8 = 11 · 36 ÷ 9 = 4 · 56 ÷ 8 = 7 · 96 ÷ 12 = 8 · 45 ÷ 9 = 5 · 6 ÷ 1 = 6 · 90 ÷ 10 = 9 · 1 ÷ 1 = 1
About this mystery
- Grade level
- Grade 4 math
- Math topics
- Rounding, Addition, Subtraction, Multiplication, Division
- Reading level
- grades 3-4
- Theme
- The Lost Island Crystal Heist — set in Misty Jungle Camp
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects