🌊 MermaidsGrade 1Reading: grades 1-2SubtractionAdditionSkip countingPlace valueMissing addends
The Case of the Missing Golden Pearl
Oh no! Someone popped the bubble vault and took the Golden Pearl. The Royal Pearl Keeper needs your help. We must search Coral Cove Reef and track down 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 | Magic Trick | Special Tool | Swimming Style | Hair Style | Fear |
|---|---|---|---|---|---|
| Wave | Wave Dash | Glow Tail | Left-finned | Pink curls | Shiny pearls |
| Coral | Kelp Grip | Crab Claw | Right-finned | Pink curls | Loud singing |
| Blue | Kelp Grip | Crab Claw | Left-finned | Blue braids | Tickly sand |
| Aquata | Coral Magic | Shell Sword | Right-finned | Blue braids | Tickly sand |
| Attina | Song Call | Star Spin | Left-finned | Pink curls | Tickly sand |
| Alana | Coral Magic | Crab Claw | Left-finned | Pink curls | Loud singing |
| Coralia | Kelp Grip | Crab Claw | Left-finned | Green locks | Loud singing |
| Shelly | Song Call | Glow Tail | Left-finned | Pink curls | Loud singing |
| Marina | Kelp Grip | Pearl Shield | Left-finned | Pink curls | Loud singing |
| Ocean | Coral Magic | Glow Tail | Right-finned | Blue braids | Tickly sand |
| Melody | Song Call | Pearl Shield | Left-finned | Pink curls | Tickly sand |
| Finny | Coral Magic | Shell Sword | Left-finned | Blue braids | Shiny pearls |
| Andrina | Wave Dash | Glow Tail | Right-finned | Green locks | Tickly sand |
| Talia | Kelp Grip | Shell Sword | Left-finned | Pink curls | Loud singing |
| Marissa | Bubble Blast | Pearl Shield | Right-finned | Pink curls | Tickly sand |
| Glimmer | Kelp Grip | Pearl Shield | Left-finned | Green locks | Tickly sand |
| Splash | Bubble Blast | Glow Tail | Left-finned | Pink curls | Tickly sand |
| Ariel | Coral Magic | Glow Tail | Left-finned | Blue braids | Tickly sand |
| Nerida | Wave Dash | Shell Sword | Left-finned | Pink curls | Loud singing |
| Adella | Song Call | Pearl Shield | Left-finned | Pink curls | Loud singing |
| Sirena | Wave Dash | Shell Sword | Right-finned | Blue braids | Loud singing |
Clue 1
Subtraction
Some starfish fell off the reef wall. Subtract the ones that floated away to find the 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
11
8
4
19
5
3
9
12
T
11
9
2
4
1
3
2
T
11
17
1
4
5
1
8
4
7
7
1
10
2
16
9
15 - 4 =T
20 - 1 =B
10 - 6 =E
13 - 8 =A
8 - 6 =O
14 - 7 =L
12 - 2 =W
20 - 4 =R
14 - 2 =I
10 - 2 =H
3 - 2 =S
19 - 2 =U
17 - 8 =D
12 - 9 =N
0/14 letters found
Clue 2
Addition
Help the little crab count his shiny sea shells. Add them together to get the next 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
5
10
20
16
8
20
19
4
15
2
20
7
2
19
12
18
16
17
12
2
16
17
12
T
5
10
T
5
10
20
13
20
9
T
5
9
12
8
1 + 4 =T
1 + 3 =K
4 + 4 =N
8 + 8 =S
6 + 12 =D
13 + 6 =A
8 + 4 =I
2 + 5 =R
5 + 8 =L
3 + 7 =H
13 + 7 =E
11 + 4 =Y
10 + 7 =W
7 + 2 =F
1 + 1 =M
0/15 letters found
Clue 3
Skip counting
Look at the school of fish. Skip count them by twos to see which way the bandit went.
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
140
22
28
T
140
22
8
28
42
22
25
T
140
28
100
110
14
30
55
100
8
16
27
8
16
27
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160T
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26H
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130L
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, ___, 30, 32E
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, ___, 60, 65D
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33G
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35A
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18O
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48F
Skip-count by 10s. Fill the blank: 10, 20, ___, 40, 50U
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20N
Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12I
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120S
0/13 letters found
Clue 4
Place value
The sea snail has piles of pearls. Group them by tens and ones to unlock this secret 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.
W
56
48
90
14
18
42
11
25
72
42
46
59
18
27
60
75
29
35
35
78
48
69
29
18
60
35
What number has 5 tens and 6 ones?W
What number has 7 tens and 8 ones?H
What number has 1 ten and 4 ones?O
What number has 9 tens and 0 ones?F
What number has 4 tens and 8 ones?E
What number has 2 tens and 7 ones?R
What number has 2 tens and 9 ones?A
What number has 7 tens and 5 ones?S
What number has 1 ten and 1 one?D
What number has 5 tens and 9 ones?C
What number has 7 tens and 2 ones?I
What number has 4 tens and 2 ones?N
What number has 6 tens and 0 ones?L
What number has 4 tens and 6 ones?K
What number has 6 tens and 9 ones?V
What number has 2 tens and 5 ones?P
What number has 1 ten and 8 ones?U
What number has 3 tens and 5 ones?T
0/18 letters found
Clue 5
Missing addends — the last clue
The octopus is hiding some of his shiny gems. Find the missing number to get the last 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
8 + ___ = 14
3 + ___ = 13
3 + ___ = 5
3 + ___ = 10
9 + ___ = 10
10 + ___ = 19
3 + ___ = 7
6 + ___ = 14
10 + ___ = 22
9 + ___ = 12
8 + ___ = 13
Step 2 — cross out the sentence with each answer
1.The villain reaches with a strong kelp grip, then shines a bright glow tail.
2.The villain calls with a loud song, then shines a bright glow tail.
3.The villain calls with a loud song, then escapes with a quick star spin.
4.The villain uses powerful coral magic, then swings a sharp shell sword.
5.The villain calls with a loud song, then swings a sharp shell sword.
6.The villain calls with a loud song, then blocks with a pearl shield.
7.The villain shoots a huge bubble blast, then snaps a big crab claw.
8.The villain reaches with a strong kelp grip, then escapes with a quick star spin.
9.The villain uses powerful coral magic, then blocks with a pearl shield.
10.The villain uses powerful coral magic, then snaps a big crab claw.
11.The villain reaches with a strong kelp grip, then blocks with a pearl shield.
12.The villain makes a fast wave dash, then shines a bright glow tail.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Missing Golden Pearl
Culprit: Marina (Kelp Grip · Pearl Shield · Left-finned · Pink curls · Loud singing)
- Clue 1 (Subtraction): "THE BANDIT DOES NOT USE A SHELL SWORD"15 - 4 = 11 (T) · 20 - 1 = 19 (B) · 10 - 6 = 4 (E) · 13 - 8 = 5 (A) · 8 - 6 = 2 (O) · 14 - 7 = 7 (L) · 12 - 2 = 10 (W) · 20 - 4 = 16 (R) · 14 - 2 = 12 (I) · 10 - 2 = 8 (H) · 3 - 2 = 1 (S) · 19 - 2 = 17 (U) · 17 - 8 = 9 (D) · 12 - 9 = 3 (N)
- Clue 2 (Addition): "THE SNEAKY MERMAID SWIMS WITH THE LEFT FIN"1 + 4 = 5 (T) · 1 + 3 = 4 (K) · 4 + 4 = 8 (N) · 8 + 8 = 16 (S) · 6 + 12 = 18 (D) · 13 + 6 = 19 (A) · 8 + 4 = 12 (I) · 2 + 5 = 7 (R) · 5 + 8 = 13 (L) · 3 + 7 = 10 (H) · 13 + 7 = 20 (E) · 11 + 4 = 15 (Y) · 10 + 7 = 17 (W) · 7 + 2 = 9 (F) · 1 + 1 = 2 (M)
- Clue 3 (Skip counting): "THE THIEF HATES LOUD SINGING"Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160 = 140 (T) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26 = 22 (H) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130 = 110 (L) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, ___, 30, 32 = 28 (E) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, ___, 60, 65 = 55 (D) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33 = 27 (G) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35 = 25 (A) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18 = 14 (O) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48 = 42 (F) · Skip-count by 10s. Fill the blank: 10, 20, ___, 40, 50 = 30 (U) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20 = 16 (N) · Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12 = 8 (I) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120 = 100 (S)
- Clue 4 (Place value): "WE FOUND PINK CURLS AT THE VAULT"What number has 5 tens and 6 ones? = 56 (W) · What number has 7 tens and 8 ones? = 78 (H) · What number has 1 ten and 4 ones? = 14 (O) · What number has 9 tens and 0 ones? = 90 (F) · What number has 4 tens and 8 ones? = 48 (E) · What number has 2 tens and 7 ones? = 27 (R) · What number has 2 tens and 9 ones? = 29 (A) · What number has 7 tens and 5 ones? = 75 (S) · What number has 1 ten and 1 one? = 11 (D) · What number has 5 tens and 9 ones? = 59 (C) · What number has 7 tens and 2 ones? = 72 (I) · What number has 4 tens and 2 ones? = 42 (N) · What number has 6 tens and 0 ones? = 60 (L) · What number has 4 tens and 6 ones? = 46 (K) · What number has 6 tens and 9 ones? = 69 (V) · What number has 2 tens and 5 ones? = 25 (P) · What number has 1 ten and 8 ones? = 18 (U) · What number has 3 tens and 5 ones? = 35 (T)
- Clue 5 (Missing addends): surviving statement (box 11) → Marina8 + ___ = 14 = 6 · 3 + ___ = 13 = 10 · 3 + ___ = 5 = 2 · 3 + ___ = 10 = 7 · 9 + ___ = 10 = 1 · 10 + ___ = 19 = 9 · 3 + ___ = 7 = 4 · 6 + ___ = 14 = 8 · 10 + ___ = 22 = 12 · 9 + ___ = 12 = 3 · 8 + ___ = 13 = 5
About this mystery
- Grade level
- Grade 1 math
- Math topics
- Subtraction, Addition, Skip counting, Place value, Missing addends
- Reading level
- grades 1-2
- Theme
- The Case of the Missing Golden Pearl — set in Coral Cove Reef
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects