🌊 Mermaids, Cats, UnicornsGrade 1Reading: grades 1-2AdditionSubtractionSkip countingPlace valueMissing addends
The Case of the Missing Star Crystal
Someone snatched the shiny star crystal from Coral Cat Lagoon. Detective, check the clues to find the sneaky 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 Spell | Unicorn Gem | Paw Style | Fur Color | Weakness |
|---|---|---|---|---|---|
| Sunny Tail | Bubble Shield | Sun Ruby | Left Paw | Pink Fur | Bright Lights |
| Magic Mittens | Star Glow | Sea Pearl | Right Paw | Blue Fur | Cold Water |
| Ocean Meow | Bubble Shield | Cloud Diamond | Left Paw | Blue Fur | Loud Bells |
| Sandy Claws | Star Glow | Moon Sapphire | Left Paw | Blue Fur | Cold Water |
| Splashy Fuzz | Splash Wave | Sun Ruby | Left Paw | Pink Fur | Bright Lights |
| Velvet Fins | Rainbow Beam | Star Emerald | Right Paw | Blue Fur | Cold Water |
| Marina Kitten | Rainbow Beam | Star Emerald | Left Paw | Pink Fur | Loud Bells |
| Bubbles Tail | Star Glow | Cloud Diamond | Left Paw | Blue Fur | Cold Water |
| Coral Paws | Rainbow Beam | Star Emerald | Right Paw | Purple Fur | Cold Water |
| Misty Paw | Sparkle Whistle | Star Emerald | Right Paw | Purple Fur | Loud Bells |
| Star Tail | Sparkle Whistle | Sea Pearl | Left Paw | Pink Fur | Cold Water |
| Salty Whiskers | Bubble Shield | Cloud Diamond | Left Paw | Blue Fur | Cold Water |
| Glimmer Paws | Rainbow Beam | Sun Ruby | Right Paw | Pink Fur | Loud Bells |
| Dolphin Meow | Splash Wave | Sun Ruby | Left Paw | Blue Fur | Loud Bells |
| Twinkle Horn | Star Glow | Sea Pearl | Left Paw | Blue Fur | Bright Lights |
| Captain Purr | Rainbow Beam | Star Emerald | Left Paw | Blue Fur | Cold Water |
| Wavey Whiskers | Sparkle Whistle | Moon Sapphire | Right Paw | Blue Fur | Bright Lights |
| Ziggy Seacat | Sparkle Whistle | Sun Ruby | Left Paw | Blue Fur | Cold Water |
| Sparkle Horn | Star Glow | Sea Pearl | Left Paw | Blue Fur | Loud Bells |
| Finny Cat | Star Glow | Moon Sapphire | Left Paw | Purple Fur | Bright Lights |
| Cleo Shell | Rainbow Beam | Star Emerald | Right Paw | Pink Fur | Loud Bells |
Clue 1
Addition
We count all the seashells found near the underwater cave to get our 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
3
10
9
5
13
11
11
4
13
20
19
12
9
2
20
12
T
3
16
2
9
4
2
T
3
4
8
9
14
9
8
4
11
19
1 + 2 =T
6 + 8 =M
7 + 6 =I
4 + 1 =V
5 + 11 =U
1 + 1 =S
6 + 2 =R
3 + 9 =O
10 + 9 =D
7 + 13 =N
5 + 5 =H
5 + 6 =L
3 + 1 =A
6 + 3 =E
0/14 letters found
Clue 2
Subtraction
Some fish swam away from the net leaving only a few left to count.
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
1
15
9
12
16
6
6
6
4
W
1
4
9
18
15
16
7
8
6
15
12
14
9
18
16
5
16
7
9
2
4
W
1
8 - 7 =W
7 - 5 =P
13 - 4 =T
16 - 9 =F
18 - 2 =E
17 - 2 =I
10 - 6 =A
17 - 3 =G
19 - 7 =N
11 - 5 =S
20 - 2 =H
8 - 3 =L
9 - 1 =U
0/13 letters found
Clue 3
Skip counting
We count the shiny pearl beads by twos along the coral reef.
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
42
25
36
39
40
65
65
10
40
18
24
10
18
10
22
10
120
26
24
45
14
33
45
65
50
22
10
T
42
36
24
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48T
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, ___, 55, 60D
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, ___, 28, 30F
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, ___, 130, 140Y
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26W
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, ___, 27, 30R
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, ___, 42, 45V
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42E
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18M
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, ___, 12, 14A
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75L
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35H
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55O
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ___, 36, 39C
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, ___, 45, 50I
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, ___, 21, 24N
0/16 letters found
Clue 4
Place value
The treasure map lists tens and ones to show the secret room 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.
F
93
47
23
22
19
24
99
85
22
81
58
11
86
58
23
11
F
93
23
43
24
69
69
74
11
99
83
11
22
11
What number has 9 tens and 3 ones?F
What number has 2 tens and 2 ones?N
What number has 9 tens and 9 ones?S
What number has 2 tens and 4 ones?A
What number has 7 tens and 4 ones?H
What number has 1 ten and 1 one?E
What number has 4 tens and 7 ones?O
What number has 4 tens and 3 ones?R
What number has 1 ten and 9 ones?D
What number has 8 tens and 1 one?G
What number has 8 tens and 3 ones?C
What number has 8 tens and 5 ones?I
What number has 5 tens and 8 ones?L
What number has 2 tens and 3 ones?U
What number has 8 tens and 6 ones?B
What number has 6 tens and 9 ones?T
0/16 letters found
Clue 5
Missing addends — the last clue
We need to find how many more magic gems fill the empty chest.
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
2 + ___ = 13
7 + ___ = 11
2 + ___ = 7
5 + ___ = 6
2 + ___ = 8
10 + ___ = 19
10 + ___ = 20
8 + ___ = 11
7 + ___ = 9
9 + ___ = 16
4 + ___ = 16
Step 2 — cross out the sentence with each answer
1.The villain casts a bubble shield, then shows a sea pearl.
2.The villain plays a sparkle whistle, then activates a star emerald.
3.The villain makes a splash wave, then activates a star emerald.
4.The villain casts a bubble shield, then wears a cloud diamond.
5.The villain creates a star glow, then wears a cloud diamond.
6.The villain makes a splash wave, then shows a sea pearl.
7.The villain plays a sparkle whistle, then wears a cloud diamond.
8.The villain plays a sparkle whistle, then shines a sun ruby.
9.The villain plays a sparkle whistle, then shows a sea pearl.
10.The villain plays a sparkle whistle, then holds a moon sapphire.
11.The villain creates a star glow, then holds a moon sapphire.
12.The villain creates a star glow, then shows a sea pearl.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Missing Star Crystal
Culprit: Ziggy Seacat (Sparkle Whistle · Sun Ruby · Left Paw · Blue Fur · Cold Water)
- Clue 1 (Addition): "THE VILLAIN DOES NOT USE A STAR EMERALD"1 + 2 = 3 (T) · 6 + 8 = 14 (M) · 7 + 6 = 13 (I) · 4 + 1 = 5 (V) · 5 + 11 = 16 (U) · 1 + 1 = 2 (S) · 6 + 2 = 8 (R) · 3 + 9 = 12 (O) · 10 + 9 = 19 (D) · 7 + 13 = 20 (N) · 5 + 5 = 10 (H) · 5 + 6 = 11 (L) · 3 + 1 = 4 (A) · 6 + 3 = 9 (E)
- Clue 2 (Subtraction): "WITNESS SAW A THIEF USING THE LEFT PAW"8 - 7 = 1 (W) · 7 - 5 = 2 (P) · 13 - 4 = 9 (T) · 16 - 9 = 7 (F) · 18 - 2 = 16 (E) · 17 - 2 = 15 (I) · 10 - 6 = 4 (A) · 17 - 3 = 14 (G) · 19 - 7 = 12 (N) · 11 - 5 = 6 (S) · 20 - 2 = 18 (H) · 8 - 3 = 5 (L) · 9 - 1 = 8 (U)
- Clue 3 (Skip counting): "THE VILLAIN RAN AWAY FROM COLD WATER"Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48 = 42 (T) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, ___, 55, 60 = 50 (D) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, ___, 28, 30 = 26 (F) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, ___, 130, 140 = 120 (Y) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26 = 22 (W) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, ___, 27, 30 = 24 (R) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, ___, 42, 45 = 39 (V) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42 = 36 (E) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18 = 14 (M) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, ___, 12, 14 = 10 (A) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75 = 65 (L) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, ___, 30, 35 = 25 (H) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55 = 45 (O) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ___, 36, 39 = 33 (C) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, ___, 45, 50 = 40 (I) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, ___, 21, 24 = 18 (N)
- Clue 4 (Place value): "FOUND A SINGLE BLUE FUR AT THE SCENE"What number has 9 tens and 3 ones? = 93 (F) · What number has 2 tens and 2 ones? = 22 (N) · What number has 9 tens and 9 ones? = 99 (S) · What number has 2 tens and 4 ones? = 24 (A) · What number has 7 tens and 4 ones? = 74 (H) · What number has 1 ten and 1 one? = 11 (E) · What number has 4 tens and 7 ones? = 47 (O) · What number has 4 tens and 3 ones? = 43 (R) · What number has 1 ten and 9 ones? = 19 (D) · What number has 8 tens and 1 one? = 81 (G) · What number has 8 tens and 3 ones? = 83 (C) · What number has 8 tens and 5 ones? = 85 (I) · What number has 5 tens and 8 ones? = 58 (L) · What number has 2 tens and 3 ones? = 23 (U) · What number has 8 tens and 6 ones? = 86 (B) · What number has 6 tens and 9 ones? = 69 (T)
- Clue 5 (Missing addends): surviving statement (box 8) → Ziggy Seacat2 + ___ = 13 = 11 · 7 + ___ = 11 = 4 · 2 + ___ = 7 = 5 · 5 + ___ = 6 = 1 · 2 + ___ = 8 = 6 · 10 + ___ = 19 = 9 · 10 + ___ = 20 = 10 · 8 + ___ = 11 = 3 · 7 + ___ = 9 = 2 · 9 + ___ = 16 = 7 · 4 + ___ = 16 = 12
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 Missing Star Crystal — set in Coral Cat Lagoon
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects