Grade 4Reading: grades 1-2Place valueAdditionSubtractionSkip countingDivision
Mystery of Sunken Castle Island
Someone snuck into camp and stole the ancient island map! You must check the clues and find out who did 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 | Primary Gear | Backup Tool | Dominant Hand | Hair Color | Stopping Item |
|---|---|---|---|---|---|
| Scout Owen | rope launcher | signal flare | left handed | jet black | sticky sap |
| Scout Penny | glider wings | smoke bombs | left handed | bright orange | sea salt spray |
| Pilot Jack | brass telescope | signal flare | right handed | bright orange | sticky sap |
| Diver Zoe | golden compass | magnetic boots | left handed | jet black | sea salt spray |
| Ranger Ella | glider wings | signal flare | right handed | jet black | sea salt spray |
| Officer Dan | golden compass | smoke bombs | left handed | bright orange | sea salt spray |
| Ranger Sam | brass telescope | smoke bombs | right handed | bright orange | sea salt spray |
| Sailor Eli | golden compass | mini drone | left handed | jet black | sticky sap |
| Pioneer Isla | glider wings | signal flare | left handed | neon green | sticky sap |
| Pioneer Lily | brass telescope | signal flare | right handed | neon green | sea salt spray |
| Climber Max | brass telescope | bright flashlight | right handed | bright orange | sea salt spray |
| Navigator Maya | golden compass | mini drone | left handed | bright orange | sticky sap |
| Surveyor Noah | golden compass | magnetic boots | left handed | jet black | loud whistle |
| Tracker Luke | brass telescope | smoke bombs | right handed | jet black | loud whistle |
| Hiker Grace | brass telescope | mini drone | right handed | bright orange | sea salt spray |
| Captain Barnaby | brass telescope | smoke bombs | left handed | jet black | sticky sap |
| Trail Guide Ben | rope launcher | signal flare | right handed | neon green | sea salt spray |
| Pilot Cole | golden compass | signal flare | left handed | bright orange | sea salt spray |
| Wayfinder Mia | rope launcher | signal flare | right handed | bright orange | sticky sap |
| Hiker Chloe | brass telescope | magnetic boots | right handed | bright orange | sea salt spray |
| Tracker Ruby | glider wings | bright flashlight | right handed | bright orange | sea salt spray |
Clue 1
Place value
You find a locked box on the beach. Look at the numbers on the lock to open it.
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
90
8000
3000
40
2000
700
700
20
2000
400
10
5000
3000
600
400
5000
T
90
60
600
3000
900
20
70
400
3000
T
90
2000
6000
300
5000
5000
T
90
600
What is the value of the 9 in 190?T
What is the value of the 6 in 165?U
What is the value of the 2 in 42,145?I
What is the value of the 2 in 923?A
What is the value of the 4 in 430?N
What is the value of the 7 in 754?L
What is the value of the 4 in 2,140?V
What is the value of the 3 in 3,277?E
What is the value of the 3 in 374?B
What is the value of the 6 in 9,682?S
What is the value of the 7 in 372?G
What is the value of the 8 in 38,615?H
What is the value of the 5 in 5,629?O
What is the value of the 6 in 6,075?C
What is the value of the 1 in 2,512?D
What is the value of the 9 in 1,982?M
0/16 letters found
Clue 2
Addition
You check the camp supplies. Count the extra gear to see what was stolen.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
P
6234
6049
8907
3970
4660
8699
8699
4707
9199
4581
4660
4707
5568
6998
8907
2856
2856
3071
8907
3970
4581
3071
8699
6049
8907
9667
4707
4660
4707
3071
3970
2817
5568
2817
2796 + 3438 =P
5401 + 4266 =G
1443 + 1413 =L
5482 + 3425 =I
1815 + 4234 =R
4265 + 2733 =V
2797 + 5902 =S
1700 + 3868 =E
2910 + 1750 =T
1889 + 2818 =H
1668 + 2913 =W
3748 + 5451 =O
1362 + 1709 =A
1221 + 1596 =D
2203 + 1767 =N
0/15 letters found
Clue 3
Subtraction
You find footprints in the mud. Subtract the old steps to track the thief.
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
8209
4089
7031
8927
7211
7031
1914
8837
6858
1914
8927
8927
T
8209
6267
3745
3745
7031
8597
2364
7360
8927
7031
1914
8927
1914
3858
T
8209
8927
3745
2632
1914
7360
11489 - 3280 =T
3955 - 97 =L
8355 - 4610 =P
3916 - 2002 =A
5956 - 1867 =H
6398 - 131 =O
10970 - 3939 =E
4489 - 2125 =B
7406 - 46 =Y
8772 - 1914 =W
10309 - 1472 =K
9363 - 766 =D
9196 - 269 =S
11601 - 4390 =N
5257 - 2625 =R
0/15 letters found
Clue 4
Skip counting
You spot trail signs on trees. Skip count the painted dots to follow the path.
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
39
45
35
20
6
16
12
45
90
14
20
21
6
90
35
45
60
90
140
24
21
36
16
12
14
90
B
39
45
90
14
70
6
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, ___, 42, 45B
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160S
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, ___, 75, 80C
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55R
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, ___, 26, 28L
Skip-count by 2s. Fill the blank: 2, 4, ___, 8, 10H
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20T
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, ___, 100, 110A
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, ___, 14, 16O
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24G
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, ___, 70, 80W
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18N
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27E
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42F
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45I
0/15 letters found
Clue 5
Division facts (1-12) — the last clue
You divide the clue cards with your team. Share them equally to solve the puzzle.
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
11 ÷ 11 = ?
77 ÷ 11 = ?
70 ÷ 7 = ?
99 ÷ 11 = ?
55 ÷ 11 = ?
108 ÷ 9 = ?
66 ÷ 11 = ?
110 ÷ 10 = ?
4 ÷ 1 = ?
24 ÷ 12 = ?
16 ÷ 2 = ?
Step 2 — cross out the sentence with each answer
1.The villain spied on the camp with a brass telescope, then scouted ahead using a mini drone.
2.The villain blocked the doorway with a heavy shield, then scouted ahead using a mini drone.
3.The villain spied on the camp with a brass telescope, then lit up the trail with a bright flashlight.
4.The villain swung across the canyon with a rope launcher, then marched up the metal wall with magnetic boots.
5.The villain swung across the canyon with a rope launcher, then lit up the trail with a bright flashlight.
6.The villain soared off the cliff with glider wings, then marked the exit with a signal flare.
7.The villain spied on the camp with a brass telescope, then vanished behind dark smoke bombs.
8.The villain swung across the canyon with a rope launcher, then vanished behind dark smoke bombs.
9.The villain soared off the cliff with glider wings, then scouted ahead using a mini drone.
10.The villain soared off the cliff with glider wings, then lit up the trail with a bright flashlight.
11.The villain soared off the cliff with glider wings, then vanished behind dark smoke bombs.
12.The villain swung across the canyon with a rope launcher, then scouted ahead using a mini drone.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — Mystery of Sunken Castle Island
Culprit: Climber Max (brass telescope · bright flashlight · right handed · bright orange · sea salt spray)
- Clue 1 (Place value): "THE VILLAIN DOES NOT USE MAGNETIC BOOTS"What is the value of the 9 in 190? = 90 (T) · What is the value of the 6 in 165? = 60 (U) · What is the value of the 2 in 42,145? = 2000 (I) · What is the value of the 2 in 923? = 20 (A) · What is the value of the 4 in 430? = 400 (N) · What is the value of the 7 in 754? = 700 (L) · What is the value of the 4 in 2,140? = 40 (V) · What is the value of the 3 in 3,277? = 3000 (E) · What is the value of the 3 in 374? = 300 (B) · What is the value of the 6 in 9,682? = 600 (S) · What is the value of the 7 in 372? = 70 (G) · What is the value of the 8 in 38,615? = 8000 (H) · What is the value of the 5 in 5,629? = 5000 (O) · What is the value of the 6 in 6,075? = 6000 (C) · What is the value of the 1 in 2,512? = 10 (D) · What is the value of the 9 in 1,982? = 900 (M)
- Clue 2 (Addition): "PRINTS SHOW THE VILLAIN WAS RIGHT HANDED"2796 + 3438 = 6234 (P) · 5401 + 4266 = 9667 (G) · 1443 + 1413 = 2856 (L) · 5482 + 3425 = 8907 (I) · 1815 + 4234 = 6049 (R) · 4265 + 2733 = 6998 (V) · 2797 + 5902 = 8699 (S) · 1700 + 3868 = 5568 (E) · 2910 + 1750 = 4660 (T) · 1889 + 2818 = 4707 (H) · 1668 + 2913 = 4581 (W) · 3748 + 5451 = 9199 (O) · 1362 + 1709 = 3071 (A) · 1221 + 1596 = 2817 (D) · 2203 + 1767 = 3970 (N)
- Clue 3 (Subtraction): "THE SNEAK WAS STOPPED BY SEA SALT SPRAY"11489 - 3280 = 8209 (T) · 3955 - 97 = 3858 (L) · 8355 - 4610 = 3745 (P) · 3916 - 2002 = 1914 (A) · 5956 - 1867 = 4089 (H) · 6398 - 131 = 6267 (O) · 10970 - 3939 = 7031 (E) · 4489 - 2125 = 2364 (B) · 7406 - 46 = 7360 (Y) · 8772 - 1914 = 6858 (W) · 10309 - 1472 = 8837 (K) · 9363 - 766 = 8597 (D) · 9196 - 269 = 8927 (S) · 11601 - 4390 = 7211 (N) · 5257 - 2625 = 2632 (R)
- Clue 4 (Skip counting): "BRIGHT ORANGE HAIR WAS LEFT ON A BRANCH"Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, ___, 42, 45 = 39 (B) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160 = 140 (S) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, ___, 75, 80 = 70 (C) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55 = 45 (R) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, ___, 26, 28 = 24 (L) · Skip-count by 2s. Fill the blank: 2, 4, ___, 8, 10 = 6 (H) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20 = 16 (T) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, ___, 100, 110 = 90 (A) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, ___, 14, 16 = 12 (O) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24 = 20 (G) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, ___, 70, 80 = 60 (W) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18 = 14 (N) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27 = 21 (E) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42 = 36 (F) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45 = 35 (I)
- Clue 5 (Division facts (1-12)): surviving statement (box 3) → Climber Max11 ÷ 11 = 1 · 77 ÷ 11 = 7 · 70 ÷ 7 = 10 · 99 ÷ 11 = 9 · 55 ÷ 11 = 5 · 108 ÷ 9 = 12 · 66 ÷ 11 = 6 · 110 ÷ 10 = 11 · 4 ÷ 1 = 4 · 24 ÷ 12 = 2 · 16 ÷ 2 = 8
About this mystery
- Grade level
- Grade 4 math
- Math topics
- Place value, Addition, Subtraction, Skip counting, Division
- Reading level
- grades 1-2
- Theme
- Mystery of Sunken Castle Island — set in a tropical island full of hidden ruins
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects