Grade 4Reading: grades 3-4AdditionRoundingSubtractionMultiplicationDivision
Mystery at Lost Fern Island
The golden trophy has been stolen from the Fern Island Camp lodge! Solve the math clues to uncover which explorer took it.
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 | Explorer Skill | Special Tool | Dominant Hand | Hair Color | Secret Fear |
|---|---|---|---|---|---|
| Ranger Noah | Zipline Gliding | Grappling Hook | Right Handed | Sun Blonde Hair | Fear Of Frogs |
| Guide Grace | Vine Swinging | Binoculars | Right Handed | Bright Red Hair | Fear Of Bats |
| Navigator Mia | Vine Swinging | Torch Lantern | Right Handed | Bright Red Hair | Fear Of Frogs |
| Navigator Luke | Zipline Gliding | Decoder Ring | Right Handed | Bright Red Hair | Fear Of Frogs |
| Ranger Toby | Map Reading | Torch Lantern | Right Handed | Sun Blonde Hair | Fear Of Bees |
| Hiker Finn | Zipline Gliding | Torch Lantern | Right Handed | Bright Red Hair | Fear Of Frogs |
| Scout Ella | Map Reading | Grappling Hook | Right Handed | Bright Red Hair | Fear Of Frogs |
| Ranger Owen | Animal Mimicry | Grappling Hook | Right Handed | Sun Blonde Hair | Fear Of Bees |
| Explorer Chloe | Vine Swinging | Golden Compass | Right Handed | Bright Red Hair | Fear Of Bees |
| Pathfinder Eli | Map Reading | Grappling Hook | Right Handed | Sun Blonde Hair | Fear Of Bees |
| Scout Leo | Zipline Gliding | Binoculars | Left Handed | Bright Red Hair | Fear Of Frogs |
| Tracker Zoe | Vine Swinging | Binoculars | Left Handed | Dark Black Hair | Fear Of Bees |
| Adventurer Kai | Animal Mimicry | Torch Lantern | Right Handed | Bright Red Hair | Fear Of Frogs |
| Hiker Nina | Zipline Gliding | Golden Compass | Right Handed | Dark Black Hair | Fear Of Frogs |
| Pathfinder Max | Vine Swinging | Decoder Ring | Left Handed | Sun Blonde Hair | Fear Of Frogs |
| Explorer Ava | River Rafting | Decoder Ring | Left Handed | Dark Black Hair | Fear Of Bees |
| Captain Bob | River Rafting | Decoder Ring | Right Handed | Dark Black Hair | Fear Of Bats |
| Tracker Lily | Zipline Gliding | Decoder Ring | Right Handed | Dark Black Hair | Fear Of Frogs |
| Guide Ruby | Zipline Gliding | Grappling Hook | Right Handed | Sun Blonde Hair | Fear Of Bees |
| Explorer Maya | River Rafting | Binoculars | Left Handed | Bright Red Hair | Fear Of Bats |
| Scout Ivy | Animal Mimicry | Binoculars | Left Handed | Sun Blonde Hair | Fear Of Bats |
Clue 1
Addition
Ranger Sam counts all the footprints left near the riverbank to gather our first big 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
8106
3959
7687
2531
6675
5531
3996
4216
7687
4300
8069
5531
3273
2322
T
8106
3273
9845
7687
6704
5531
9845
T
8106
6675
6704
7687
8069
3996
5192
8069
5428
5428
4216
2322
5531
3996
3959
9845
9845
2698
4175 + 3931 =T
4366 + 2338 =S
1326 + 2633 =H
2691 + 1305 =G
1888 + 3643 =N
2500 + 4175 =U
2308 + 1908 =L
1533 + 1165 =K
2743 + 1557 =B
1420 + 1853 =D
4117 + 3570 =E
1593 + 729 =I
3295 + 6550 =O
4831 + 3238 =A
3148 + 2280 =P
1565 + 966 =J
3531 + 1661 =R
0/17 letters found
Clue 2
Rounding
The digital camp scanner rounds the weight of the missing supplies on its screen.
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
300
70
900
30
20
20
T
300
9000
90
370
50
T
300
2300
2300
70
20
230
430
2300
T
300
90
20
50
1300
90
370
1300
70
T
300
70
430
50
290
1300
90
370
9000
Round 286 to the nearest hundredT
Round 1,315 to the nearest hundredG
Round 71 to the nearest tenH
Round 17 to the nearest tenO
Round 430 to the nearest tenA
Round 288 to the nearest tenD
Round 234 to the nearest tenW
Round 944 to the nearest hundredE
Round 30 to the nearest tenF
Round 370 to the nearest tenI
Round 8,566 to the nearest thousandP
Round 94 to the nearest tenR
Round 50 to the nearest tenN
Round 2,297 to the nearest hundredS
0/14 letters found
Clue 3
Subtraction
Maya compares the gear left in the shed to see how many items were taken.
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
3041
4604
8388
2419
1480
6499
6499
8118
1480
3034
6343
8118
3034
8118
6014
8118
3110
6014
4604
8388
3034
8118
6823
6343
5269
8624
6071
6343
5269
8118
8044
8388
8349
3864 - 823 =T
11716 - 3367 =D
7263 - 440 =F
10762 - 2374 =E
6320 - 306 =W
7021 - 678 =R
8035 - 3431 =H
3258 - 148 =Y
9455 - 1337 =A
10413 - 1789 =G
5326 - 57 =O
4020 - 1601 =V
6966 - 467 =L
5479 - 2445 =N
8570 - 2499 =C
9810 - 1766 =K
5545 - 4065 =I
0/17 letters found
Clue 4
Multiplication facts (1-12)
Scout Leo finds equal rows of supply crates hidden behind the thick vines.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
R
55
5
88
77
64
108
R
55
3
2
R
55
64
32
88
3
11
5
R
55
5
84
5
81
2
9
32
2
77
5
21
64
14
2
64
28
84
5
5 × 11 =R
7 × 3 =M
8 × 8 =A
2 × 7 =P
5 × 1 =E
1 × 3 =S
9 × 1 =O
1 × 2 =T
4 × 7 =B
9 × 9 =F
8 × 4 =N
11 × 1 =W
11 × 8 =D
7 × 11 =H
7 × 12 =L
9 × 12 =I
0/16 letters found
Clue 5
Division facts (1-12) — the last clue
The team splits the ancient coins into equal piles to unlock the final clue 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
48 ÷ 12 = ?
18 ÷ 2 = ?
120 ÷ 12 = ?
24 ÷ 12 = ?
42 ÷ 7 = ?
12 ÷ 1 = ?
35 ÷ 7 = ?
24 ÷ 3 = ?
5 ÷ 5 = ?
70 ÷ 10 = ?
27 ÷ 9 = ?
Step 2 — cross out the sentence with each answer
1.The villain mimicked a wild jungle parrot, then guided the path with a golden compass.
2.The villain swung across the gorge on vines, then unlocked the chest with a decoder ring.
3.The villain swung across the gorge on vines, then spotted the campsite using binoculars.
4.The villain mimicked a wild jungle parrot, then lit up the trail with a torch lantern.
5.The villain mimicked a wild jungle parrot, then spotted the campsite using binoculars.
6.The villain glided down the zipline, then scaled the canyon with a grappling hook.
7.The villain decoded the secret island map, then scaled the canyon with a grappling hook.
8.The villain paddled down the rapid river, then guided the path with a golden compass.
9.The villain swung across the gorge on vines, then lit up the trail with a torch lantern.
10.The villain glided down the zipline, then unlocked the chest with a decoder ring.
11.The villain glided down the zipline, then lit up the trail with a torch lantern.
12.The villain paddled down the rapid river, then lit up the trail with a torch lantern.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — Mystery at Lost Fern Island
Culprit: Hiker Finn (Zipline Gliding · Torch Lantern · Right Handed · Bright Red Hair · Fear Of Frogs)
- Clue 1 (Addition): "THE JUNGLE BANDIT DOES NOT USE A GRAPPLING HOOK"4175 + 3931 = 8106 (T) · 4366 + 2338 = 6704 (S) · 1326 + 2633 = 3959 (H) · 2691 + 1305 = 3996 (G) · 1888 + 3643 = 5531 (N) · 2500 + 4175 = 6675 (U) · 2308 + 1908 = 4216 (L) · 1533 + 1165 = 2698 (K) · 2743 + 1557 = 4300 (B) · 1420 + 1853 = 3273 (D) · 4117 + 3570 = 7687 (E) · 1593 + 729 = 2322 (I) · 3295 + 6550 = 9845 (O) · 4831 + 3238 = 8069 (A) · 3148 + 2280 = 5428 (P) · 1565 + 966 = 2531 (J) · 3531 + 1661 = 5192 (R)
- Clue 2 (Rounding): "THE FOOTPRINTS SHOW A STRONG RIGHT HAND GRIP"Round 286 to the nearest hundred = 300 (T) · Round 1,315 to the nearest hundred = 1300 (G) · Round 71 to the nearest ten = 70 (H) · Round 17 to the nearest ten = 20 (O) · Round 430 to the nearest ten = 430 (A) · Round 288 to the nearest ten = 290 (D) · Round 234 to the nearest ten = 230 (W) · Round 944 to the nearest hundred = 900 (E) · Round 30 to the nearest ten = 30 (F) · Round 370 to the nearest ten = 370 (I) · Round 8,566 to the nearest thousand = 9000 (P) · Round 94 to the nearest ten = 90 (R) · Round 50 to the nearest ten = 50 (N) · Round 2,297 to the nearest hundred = 2300 (S)
- Clue 3 (Subtraction): "THE VILLAIN RAN AWAY WHEN A FROG CROAKED"3864 - 823 = 3041 (T) · 11716 - 3367 = 8349 (D) · 7263 - 440 = 6823 (F) · 10762 - 2374 = 8388 (E) · 6320 - 306 = 6014 (W) · 7021 - 678 = 6343 (R) · 8035 - 3431 = 4604 (H) · 3258 - 148 = 3110 (Y) · 9455 - 1337 = 8118 (A) · 10413 - 1789 = 8624 (G) · 5326 - 57 = 5269 (O) · 4020 - 1601 = 2419 (V) · 6966 - 467 = 6499 (L) · 5479 - 2445 = 3034 (N) · 8570 - 2499 = 6071 (C) · 9810 - 1766 = 8044 (K) · 5545 - 4065 = 1480 (I)
- Clue 4 (Multiplication facts (1-12)): "RED HAIR STRANDS WERE LEFT ON THE MAP TABLE"5 × 11 = 55 (R) · 7 × 3 = 21 (M) · 8 × 8 = 64 (A) · 2 × 7 = 14 (P) · 5 × 1 = 5 (E) · 1 × 3 = 3 (S) · 9 × 1 = 9 (O) · 1 × 2 = 2 (T) · 4 × 7 = 28 (B) · 9 × 9 = 81 (F) · 8 × 4 = 32 (N) · 11 × 1 = 11 (W) · 11 × 8 = 88 (D) · 7 × 11 = 77 (H) · 7 × 12 = 84 (L) · 9 × 12 = 108 (I)
- Clue 5 (Division facts (1-12)): surviving statement (box 11) → Hiker Finn48 ÷ 12 = 4 · 18 ÷ 2 = 9 · 120 ÷ 12 = 10 · 24 ÷ 12 = 2 · 42 ÷ 7 = 6 · 12 ÷ 1 = 12 · 35 ÷ 7 = 5 · 24 ÷ 3 = 8 · 5 ÷ 5 = 1 · 70 ÷ 10 = 7 · 27 ÷ 9 = 3
About this mystery
- Grade level
- Grade 4 math
- Math topics
- Addition, Rounding, Subtraction, Multiplication, Division
- Reading level
- grades 3-4
- Theme
- Mystery at Lost Fern Island — set in Fern Island Adventure Camp
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects