🌊 MermaidsGrade 2Reading: grades 1-2AdditionSubtractionPlace valueSkip countingMissing addends
The Mystery of the Coral Crown
Oh no! Someone took the Queen's beautiful Coral Crown from the sand castle. The Reef is in trouble! We must find the sneaky mermaid who 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 | swimming trick | magic item | favorite hand | hair accessory | fears most |
|---|---|---|---|---|---|
| Glimmer | bubble blast | star wand | right handed | green kelp | loud singing |
| Nerida | kelp swing | crab shield | right handed | green kelp | tickly seaweed |
| Ariel | tide spin | crab shield | right handed | blue shell | loud singing |
| Melody | wave dash | star wand | right handed | green kelp | loud singing |
| Kelpy | tide spin | star wand | right handed | green kelp | bright light |
| Splash | wave dash | glow shell | left handed | blue shell | tickly seaweed |
| Marina | bubble blast | sea mirror | right handed | blue shell | tickly seaweed |
| Jewel | bubble blast | star wand | right handed | pink flower | tickly seaweed |
| Shelly | bubble blast | pearl ring | right handed | pink flower | bright light |
| Waverly | wave dash | pearl ring | right handed | pink flower | tickly seaweed |
| Storm | kelp swing | star wand | left handed | blue shell | loud singing |
| Finny | coral jump | star wand | left handed | blue shell | tickly seaweed |
| Starla | tide spin | pearl ring | right handed | green kelp | bright light |
| Misty | kelp swing | star wand | left handed | green kelp | tickly seaweed |
| Coralia | wave dash | sea mirror | left handed | blue shell | tickly seaweed |
| Bubbles | kelp swing | crab shield | left handed | pink flower | tickly seaweed |
| Aqua | kelp swing | sea mirror | right handed | blue shell | tickly seaweed |
| Bluebell | tide spin | glow shell | left handed | blue shell | tickly seaweed |
| Sunny | bubble blast | sea mirror | left handed | blue shell | bright light |
| Pearl | bubble blast | crab shield | left handed | blue shell | tickly seaweed |
| Sky | bubble blast | star wand | right handed | blue shell | tickly seaweed |
Clue 1
Addition
We need to count all the lost sea shells. The guard adds the white shells and the pink shells to get a total.
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
39
91
26
T
39
91
22
26
84
32
94
26
56
23
94
T
39
91
88
30
26
88
56
26
88
59
22
67
67
94
67
22 + 17 =T
25 + 59 =F
13 + 9 =I
59 + 32 =H
9 + 21 =V
23 + 33 =S
15 + 17 =D
34 + 33 =R
17 + 9 =E
39 + 20 =M
53 + 35 =A
12 + 11 =N
45 + 49 =O
0/13 letters found
Clue 2
Subtraction
The sneaky thief took some pearls. We had many pearls but now some are gone. We subtract to see how many are missing.
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
74
57
37
T
74
57
17
37
72
54
11
29
T
74
37
32
87
29
T
74
37
54
17
T
74
57
T
74
57
37
63
37
72
T
74
57
32
87
23
111 - 37 =T
34 - 23 =R
69 - 12 =H
65 - 2 =L
33 - 4 =O
63 - 26 =E
34 - 2 =A
89 - 2 =N
86 - 14 =F
57 - 3 =W
35 - 12 =D
57 - 40 =I
0/12 letters found
Clue 3
Place value
The crabs found clues in the sand. They sorted shiny stones into boxes of tens and ones.
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
45
12
11
T
45
12
83
11
20
34
50
11
11
80
11
94
33
T
45
T
45
83
67
88
74
44
34
11
33
15
11
11
94
What number has 4 tens and 5 ones?T
What number has 1 ten and 2 ones?H
What number has 2 tens and 0 ones?F
What number has 3 tens and 3 ones?A
What number has 3 tens and 4 ones?S
What number has 9 tens and 4 ones?D
What number has 4 tens and 4 ones?Y
What number has 6 tens and 7 ones?C
What number has 8 tens and 0 ones?Z
What number has 1 ten and 5 ones?W
What number has 8 tens and 3 ones?I
What number has 5 tens and 0 ones?N
What number has 8 tens and 8 ones?K
What number has 7 tens and 4 ones?L
What number has 1 ten and 1 one?E
0/15 letters found
Clue 4
Skip counting
Let us look at the starfish prints. We can count the starfish arms by skip counting by fives.
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
26
20
8
27
80
9
15
45
80
30
100
21
50
55
36
30
8
15
20
8
36
36
90
100
T
26
20
8
15
50
100
21
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, ___, 28, 30T
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27D
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42L
Skip-count by 5s. Fill the blank: 5, 10, ___, 20, 25S
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100O
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, ___, 60, 70A
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24H
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, ___, 100, 110I
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, ___, 60, 65B
Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12E
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55F
Skip-count by 10s. Fill the blank: 10, 20, ___, 40, 50U
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33C
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120N
Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15P
0/15 letters found
Clue 5
Missing addends — the last clue
The queen needs ten shiny pearls to fix her crown. She has seven pearls now. Let us find out how many more she needs.
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
3 + ___ = 4
2 + ___ = 7
3 + ___ = 7
2 + ___ = 12
6 + ___ = 18
1 + ___ = 12
2 + ___ = 9
1 + ___ = 7
10 + ___ = 12
1 + ___ = 9
4 + ___ = 7
Step 2 — cross out the sentence with each answer
1.The villain did a fast tide spin, then shined a glow shell.
2.The villain took a big kelp swing, then waved a star wand.
3.The villain took a big kelp swing, then shined a glow shell.
4.The villain made a high coral jump, then waved a star wand.
5.The villain blew a bubble blast, then held a crab shield.
6.The villain blew a bubble blast, then waved a star wand.
7.The villain blew a bubble blast, then used a pearl ring.
8.The villain made a high coral jump, then shined a glow shell.
9.The villain did a fast wave dash, then shined a glow shell.
10.The villain did a fast wave dash, then waved a star wand.
11.The villain made a high coral jump, then dropped a sea mirror.
12.The villain did a fast tide spin, then used a pearl ring.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Mystery of the Coral Crown
Culprit: Splash (wave dash · glow shell · left handed · blue shell · tickly seaweed)
- Clue 1 (Addition): "THE THIEF DOES NOT HAVE A SEA MIRROR"22 + 17 = 39 (T) · 25 + 59 = 84 (F) · 13 + 9 = 22 (I) · 59 + 32 = 91 (H) · 9 + 21 = 30 (V) · 23 + 33 = 56 (S) · 15 + 17 = 32 (D) · 34 + 33 = 67 (R) · 17 + 9 = 26 (E) · 39 + 20 = 59 (M) · 53 + 35 = 88 (A) · 12 + 11 = 23 (N) · 45 + 49 = 94 (O)
- Clue 2 (Subtraction): "THE THIEF WROTE A NOTE WITH THE LEFT HAND"111 - 37 = 74 (T) · 34 - 23 = 11 (R) · 69 - 12 = 57 (H) · 65 - 2 = 63 (L) · 33 - 4 = 29 (O) · 63 - 26 = 37 (E) · 34 - 2 = 32 (A) · 89 - 2 = 87 (N) · 86 - 14 = 72 (F) · 57 - 3 = 54 (W) · 35 - 12 = 23 (D) · 57 - 40 = 17 (I)
- Clue 3 (Place value): "THE THIEF SNEEZED AT TICKLY SEAWEED"What number has 4 tens and 5 ones? = 45 (T) · What number has 1 ten and 2 ones? = 12 (H) · What number has 2 tens and 0 ones? = 20 (F) · What number has 3 tens and 3 ones? = 33 (A) · What number has 3 tens and 4 ones? = 34 (S) · What number has 9 tens and 4 ones? = 94 (D) · What number has 4 tens and 4 ones? = 44 (Y) · What number has 6 tens and 7 ones? = 67 (C) · What number has 8 tens and 0 ones? = 80 (Z) · What number has 1 ten and 5 ones? = 15 (W) · What number has 8 tens and 3 ones? = 83 (I) · What number has 5 tens and 0 ones? = 50 (N) · What number has 8 tens and 8 ones? = 88 (K) · What number has 7 tens and 4 ones? = 74 (L) · What number has 1 ten and 1 one? = 11 (E)
- Clue 4 (Skip counting): "THE COPS FOUND A BLUE SHELL IN THE SAND"Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, ___, 28, 30 = 26 (T) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27 = 21 (D) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42 = 36 (L) · Skip-count by 5s. Fill the blank: 5, 10, ___, 20, 25 = 15 (S) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100 = 80 (O) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, ___, 60, 70 = 50 (A) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, ___, 22, 24 = 20 (H) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, ___, 100, 110 = 90 (I) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, ___, 60, 65 = 55 (B) · Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12 = 8 (E) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55 = 45 (F) · Skip-count by 10s. Fill the blank: 10, 20, ___, 40, 50 = 30 (U) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33 = 27 (C) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120 = 100 (N) · Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15 = 9 (P)
- Clue 5 (Missing addends): surviving statement (box 9) → Splash3 + ___ = 4 = 1 · 2 + ___ = 7 = 5 · 3 + ___ = 7 = 4 · 2 + ___ = 12 = 10 · 6 + ___ = 18 = 12 · 1 + ___ = 12 = 11 · 2 + ___ = 9 = 7 · 1 + ___ = 7 = 6 · 10 + ___ = 12 = 2 · 1 + ___ = 9 = 8 · 4 + ___ = 7 = 3
About this mystery
- Grade level
- Grade 2 math
- Math topics
- Addition, Subtraction, Place value, Skip counting, Missing addends
- Reading level
- grades 1-2
- Theme
- The Mystery of the Coral Crown — set in The Shimmering Reef
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects