🌊 MermaidsGrade 1Reading: grades 1-2AdditionSubtractionSkip countingPlace valueMissing addends
The Case of the Lost Pearl
Someone swam into the palace and took the Royal Pearl from Coral Cove! The Royal Reef Keeper needs your help. We must search the reef and find the mermaid sea-thief before sunset.
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 Power | Extra Power | Clue Left Behind | Hair Color | Weakness |
|---|---|---|---|---|---|
| Coralia | taming sharks | growing giant kelp | wears a shell crown | ocean blue hair | sneezes near purple sea sponge |
| Sunny | lighting up caves | hiding in sand | wears a sea star pin | seaweed green hair | afraid of tickly tickle fish |
| Shellie | lighting up caves | hiding in sand | wears a sea star pin | ocean blue hair | afraid of tickly tickle fish |
| Brooke | singing sweet songs | hiding in sand | wears a sea star pin | seaweed green hair | afraid of tickly tickle fish |
| Sandy | swimming super fast | hiding in sand | wears a shell crown | ocean blue hair | sneezes near purple sea sponge |
| Trixie | taming sharks | hiding in sand | wears a sea star pin | seaweed green hair | afraid of tickly tickle fish |
| Nerida | lighting up caves | hiding in sand | wears a shell crown | ocean blue hair | sneezes near purple sea sponge |
| Cove | lighting up caves | freezing water | wears a shell crown | ocean blue hair | afraid of tickly tickle fish |
| Opal | singing sweet songs | freezing water | wears a shell crown | ocean blue hair | afraid of tickly tickle fish |
| Delphine | singing sweet songs | freezing water | wears a shell crown | coral pink hair | afraid of tickly tickle fish |
| Finley | singing sweet songs | freezing water | wears a shell crown | ocean blue hair | gets dizzy in warm currents |
| Ariel | making bubbles | freezing water | wears a shell crown | coral pink hair | sneezes near purple sea sponge |
| Siren | singing sweet songs | hiding in sand | wears a shell crown | coral pink hair | afraid of tickly tickle fish |
| Cleo | singing sweet songs | spinning small whirlpools | wears a shell crown | coral pink hair | sneezes near purple sea sponge |
| Marina | swimming super fast | hiding in sand | wears a sea star pin | ocean blue hair | sneezes near purple sea sponge |
| Kelp | making bubbles | spinning small whirlpools | wears a shell crown | ocean blue hair | sneezes near purple sea sponge |
| Pearl | singing sweet songs | talking to crabs | wears a shell crown | coral pink hair | sneezes near purple sea sponge |
| Lulu | lighting up caves | talking to crabs | wears a sea star pin | seaweed green hair | gets dizzy in warm currents |
| Piper | making bubbles | freezing water | wears a shell crown | seaweed green hair | gets dizzy in warm currents |
| Aqua | taming sharks | freezing water | wears a shell crown | ocean blue hair | sneezes near purple sea sponge |
| Melody | lighting up caves | growing giant kelp | wears a sea star pin | seaweed green hair | gets dizzy in warm currents |
Clue 1
Addition
We find shiny seashells left on the sand. Let us add the shells together to get a 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
14
10
4
8
20
9
9
19
20
7
2
16
4
17
7
16
T
14
17
18
20
7
11
10
20
6
9
18
16
16
9
17
9 + 5 =T
8 + 8 =O
7 + 2 =L
8 + 9 =S
5 + 1 =R
8 + 3 =W
3 + 7 =H
5 + 2 =N
4 + 4 =V
1 + 1 =D
11 + 7 =P
3 + 1 =E
13 + 7 =I
7 + 12 =A
0/14 letters found
Clue 2
Subtraction
Coral the turtle has some clams but a crab took some away. Take away the crabs clams to find 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
3
10
8
17
16
17
9
8
11
T
3
6
8
1
18
17
1
17
10
8
5
5
11
18
4
6
12
10 - 7 =T
15 - 4 =C
20 - 3 =S
9 - 1 =E
17 - 7 =H
11 - 7 =O
8 - 2 =W
20 - 4 =U
13 - 4 =P
19 - 1 =R
19 - 7 =N
9 - 4 =L
6 - 5 =A
0/13 letters found
Clue 3
Skip counting
We swim past groups of sea stars. Count them by twos 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.
P
45
9
140
P
45
50
22
24
P
45
25
65
40
22
24
14
130
42
22
12
30
22
14
24
65
22
22
120
22
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55P
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, ___, 130, 140Z
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75N
Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15U
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, ___, 26, 28S
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160R
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18M
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150A
Skip-count by 10s. Fill the blank: 10, 20, 30, ___, 50, 60G
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48K
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, ___, 33, 36H
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26E
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35O
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, ___, 60, 70L
Skip-count by 3s. Fill the blank: 3, 6, 9, ___, 15, 18T
0/15 letters found
Clue 4
Place value
A secret chest is locked. The lock uses tens and ones to show the code.
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
25
73
76
97
99
61
39
45
54
99
73
97
86
73
55
61
15
55
91
72
What number has 2 tens and 5 ones?W
What number has 7 tens and 2 ones?R
What number has 9 tens and 1 one?I
What number has 7 tens and 3 ones?E
What number has 9 tens and 7 ones?O
What number has 1 ten and 5 ones?H
What number has 5 tens and 5 ones?A
What number has 9 tens and 9 ones?U
What number has 3 tens and 9 ones?D
What number has 5 tens and 4 ones?L
What number has 8 tens and 6 ones?C
What number has 6 tens and 1 one?N
What number has 4 tens and 5 ones?B
What number has 7 tens and 6 ones?F
0/14 letters found
Clue 5
Missing addends — the last clue
The Pearl Patrol needs ten bubble rings but they only have six. Find how many more they need.
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
5 + ___ = 7
1 + ___ = 4
5 + ___ = 12
2 + ___ = 14
7 + ___ = 13
10 + ___ = 19
1 + ___ = 11
1 + ___ = 2
7 + ___ = 15
2 + ___ = 6
9 + ___ = 20
Step 2 — cross out the sentence with each answer
1.The villain sang a very soft song, then grew giant kelp to block the road.
2.The villain swam fast past the reef, then hid deep in the warm sand.
3.The villain tamed a big wild shark, then froze a wall of water to escape.
4.The villain swam fast past the reef, then asked a crab to hide the key.
5.The villain tamed a big wild shark, then grew giant kelp to block the road.
6.The villain sang a very soft song, then hid deep in the warm sand.
7.The villain lit up a dark underwater cave, then hid deep in the warm sand.
8.The villain swam fast past the reef, then spun a small whirlpool to spin away.
9.The villain tamed a big wild shark, then asked a crab to hide the key.
10.The villain lit up a dark underwater cave, then spun a small whirlpool to spin away.
11.The villain blew a path of giant bubbles, then asked a crab to hide the key.
12.The villain lit up a dark underwater cave, then froze a wall of water to escape.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Lost Pearl
Culprit: Coralia (taming sharks · growing giant kelp · wears a shell crown · ocean blue hair · sneezes near purple sea sponge)
- Clue 1 (Addition): "THE VILLAIN DOES NOT SPIN WHIRLPOOLS"9 + 5 = 14 (T) · 8 + 8 = 16 (O) · 7 + 2 = 9 (L) · 8 + 9 = 17 (S) · 5 + 1 = 6 (R) · 8 + 3 = 11 (W) · 3 + 7 = 10 (H) · 5 + 2 = 7 (N) · 4 + 4 = 8 (V) · 1 + 1 = 2 (D) · 11 + 7 = 18 (P) · 3 + 1 = 4 (E) · 13 + 7 = 20 (I) · 7 + 12 = 19 (A)
- Clue 2 (Subtraction): "THE SUSPECT WEARS A SHELL CROWN"10 - 7 = 3 (T) · 15 - 4 = 11 (C) · 20 - 3 = 17 (S) · 9 - 1 = 8 (E) · 17 - 7 = 10 (H) · 11 - 7 = 4 (O) · 8 - 2 = 6 (W) · 20 - 4 = 16 (U) · 13 - 4 = 9 (P) · 19 - 1 = 18 (R) · 19 - 7 = 12 (N) · 9 - 4 = 5 (L) · 6 - 5 = 1 (A)
- Clue 3 (Skip counting): "PURPLE SPONGES MAKE THEM SNEEZE"Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55 = 45 (P) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, ___, 130, 140 = 120 (Z) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75 = 65 (N) · Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15 = 9 (U) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, ___, 26, 28 = 24 (S) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160 = 140 (R) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18 = 14 (M) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150 = 130 (A) · Skip-count by 10s. Fill the blank: 10, 20, 30, ___, 50, 60 = 40 (G) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48 = 42 (K) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, ___, 33, 36 = 30 (H) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26 = 22 (E) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35 = 25 (O) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, ___, 60, 70 = 50 (L) · Skip-count by 3s. Fill the blank: 3, 6, 9, ___, 15, 18 = 12 (T)
- Clue 4 (Place value): "WE FOUND BLUE OCEAN HAIR"What number has 2 tens and 5 ones? = 25 (W) · What number has 7 tens and 2 ones? = 72 (R) · What number has 9 tens and 1 one? = 91 (I) · What number has 7 tens and 3 ones? = 73 (E) · What number has 9 tens and 7 ones? = 97 (O) · What number has 1 ten and 5 ones? = 15 (H) · What number has 5 tens and 5 ones? = 55 (A) · What number has 9 tens and 9 ones? = 99 (U) · What number has 3 tens and 9 ones? = 39 (D) · What number has 5 tens and 4 ones? = 54 (L) · What number has 8 tens and 6 ones? = 86 (C) · What number has 6 tens and 1 one? = 61 (N) · What number has 4 tens and 5 ones? = 45 (B) · What number has 7 tens and 6 ones? = 76 (F)
- Clue 5 (Missing addends): surviving statement (box 5) → Coralia5 + ___ = 7 = 2 · 1 + ___ = 4 = 3 · 5 + ___ = 12 = 7 · 2 + ___ = 14 = 12 · 7 + ___ = 13 = 6 · 10 + ___ = 19 = 9 · 1 + ___ = 11 = 10 · 1 + ___ = 2 = 1 · 7 + ___ = 15 = 8 · 2 + ___ = 6 = 4 · 9 + ___ = 20 = 11
About this mystery
- Grade level
- Grade 1 math
- Math topics
- Addition, Subtraction, Skip counting, Place value, Missing addends
- Reading level
- grades 1-2
- Theme
- The Case of the Lost Pearl — set in Coral Cove
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects