🔎 Marine biology, books,readinGrade 5Reading: grades 5-6Fractions of a numberOrder of operationsMultiplicationRoundingDivision
The Case of the Golden Kelp
The legendary Golden Kelp Codex has been stolen from the deepest shelf of the Great Coral Library! Help the Reef Patrol trace the clues, solve the math, and identify the thief before they escape to the deepest ocean trench.
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 | Specialty Gear | Backup Equipment | Writing Style | Diving Suit Color | Dropped Snack |
|---|---|---|---|---|---|
| Cindy Van Dover | Deep Sea Sonar | Diver Helmet | Writes Right Handed | Blue Diving Suit | Dried Krill Chips |
| Robert Ballard | Clam Shell Tablet | Bioluminescent Lamp | Writes Left Handed | Blue Diving Suit | Salty Sea Grass |
| Ruth Turner | Deep Sea Sonar | Bioluminescent Lamp | Writes Left Handed | Blue Diving Suit | Salty Sea Grass |
| Enric Sala | Kelp Bookmark | Submarine Glider | Writes Left Handed | Orange Diving Suit | Plankton Puffs |
| Daniel Pauly | Coral Magnifier | Bioluminescent Lamp | Writes Right Handed | Blue Diving Suit | Dried Krill Chips |
| Samuel Stillman | Clam Shell Tablet | Submarine Glider | Writes Right Handed | Green Diving Suit | Dried Krill Chips |
| Henry Bigelow | Kelp Bookmark | Waterproof Notepad | Writes Right Handed | Orange Diving Suit | Dried Krill Chips |
| Sylvia Earle | Kelp Bookmark | Waterproof Notepad | Writes Left Handed | Blue Diving Suit | Dried Krill Chips |
| Jane Lubchenco | Deep Sea Sonar | Waterproof Notepad | Writes Right Handed | Blue Diving Suit | Salty Sea Grass |
| Edith Widder | Deep Sea Sonar | Algae Satchel | Writes Right Handed | Blue Diving Suit | Dried Krill Chips |
| Mary Sears | Coral Magnifier | Waterproof Notepad | Writes Left Handed | Blue Diving Suit | Plankton Puffs |
| Steve OShea | Squid Ink Pen | Submarine Glider | Writes Right Handed | Blue Diving Suit | Dried Krill Chips |
| Ayana Johnson | Kelp Bookmark | Bioluminescent Lamp | Writes Right Handed | Green Diving Suit | Dried Krill Chips |
| Hans Hass | Clam Shell Tablet | Waterproof Notepad | Writes Right Handed | Green Diving Suit | Dried Krill Chips |
| James Cameron | Clam Shell Tablet | Submarine Glider | Writes Left Handed | Blue Diving Suit | Salty Sea Grass |
| Eugenie Clark | Squid Ink Pen | Algae Satchel | Writes Right Handed | Green Diving Suit | Plankton Puffs |
| William Beebe | Squid Ink Pen | Bioluminescent Lamp | Writes Right Handed | Green Diving Suit | Salty Sea Grass |
| Nancy Rabalais | Deep Sea Sonar | Submarine Glider | Writes Left Handed | Green Diving Suit | Salty Sea Grass |
| Alistair Hardy | Clam Shell Tablet | Bioluminescent Lamp | Writes Left Handed | Green Diving Suit | Plankton Puffs |
| Charles Darwin | Coral Magnifier | Waterproof Notepad | Writes Left Handed | Blue Diving Suit | Dried Krill Chips |
| Marie Tharp | Deep Sea Sonar | Submarine Glider | Writes Right Handed | Blue Diving Suit | Dried Krill Chips |
Clue 1
Fractions of a number
To begin the search, we must calculate the fraction of glowing coral pages left intact on the bookshelf.
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
22
19
20
T
22
19
18
20
37
14
31
20
10
17
31
T
22
36
11
32
32
35
T
22
19
20
11
25
9
11
20
10
11
T
22
36
19
20
25
2/3 of 33 =T
2/6 of 108 =C
1/4 of 128 =R
1/3 of 33 =A
1/3 of 30 =S
3/6 of 62 =O
1/2 of 50 =L
2/10 of 85 =N
4/5 of 25 =E
1/4 of 148 =F
1/5 of 45 =G
6/10 of 30 =I
1/2 of 70 =Y
3/6 of 28 =D
2/10 of 95 =H
0/15 letters found
Clue 2
Order of operations
The library security system can be unlocked only by evaluating a complex sequence of bubble currents.
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
47
37
30
52
W
47
69
34
36
55
6
55
52
22
73
37
73
30
11
8
73
36
37
30
39
22
6
55
37
49
39
26
37
69
11 × 6 - 19 =W
4 + 7 × 5 =O
3 + 4 × 2 =M
11 × 6 - 29 =E
18 + 2 × 4 =V
10 × 6 - 8 =A
9 × 9 - 12 =R
2 + 2 × 2 =T
40 + 5 × 3 =H
4 + 2 × 2 =U
18 + 9 × 2 =G
10 × 7 - 21 =C
9 × 10 - 17 =D
6 × 6 - 6 =S
5 × 7 - 1 =I
2 × 12 - 2 =N
0/16 letters found
Clue 3
Multiplication facts (1-12)
We need to multiply the rows of sea shells to find how many seaweed bookmarks were left behind.
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
55
121
42
28
144
42
16
42
28
99
42
108
108
42
3
66
88
3
4
49
42
3
81
4
49
108
108
144
121
49
2
28
11 × 5 =T
11 × 8 =F
9 × 9 =K
4 × 1 =R
11 × 6 =O
1 × 3 =D
4 × 4 =N
7 × 6 =E
4 × 7 =S
9 × 12 =L
11 × 11 =H
12 × 12 =C
9 × 11 =M
7 × 7 =I
2 × 1 =P
0/15 letters found
Clue 4
Rounding
Our sonar scanner gives an estimate of the suspect's escape route, but the screen only shows rounded figures.
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
7000
90
5000
5000
370
5000
290
30
50
500
3700
130
130
5000
50
2900
200
1100
3000
5000
50
110
230
110
370
700
4300
3000
110
T
7000
T
7000
90
500
5000
2900
50
Round 6,574 to the nearest thousandT
Round 191 to the nearest hundredB
Round 4,521 to the nearest thousandE
Round 128 to the nearest tenP
Round 3,652 to the nearest hundredO
Round 49 to the nearest tenD
Round 226 to the nearest tenV
Round 368 to the nearest tenN
Round 4,288 to the nearest hundredS
Round 114 to the nearest tenI
Round 746 to the nearest hundredG
Round 3,257 to the nearest thousandU
Round 288 to the nearest tenM
Round 2,915 to the nearest hundredA
Round 34 to the nearest tenY
Round 540 to the nearest hundredR
Round 1,112 to the nearest hundredL
Round 90 to the nearest tenH
0/18 letters found
Clue 5
Division facts (1-12) — the last clue
We must divide a bucket of bioluminescent ink tablets equally among the patrol teams to map the trenches.
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
108 ÷ 9 = ?
55 ÷ 11 = ?
20 ÷ 2 = ?
22 ÷ 2 = ?
6 ÷ 1 = ?
24 ÷ 8 = ?
6 ÷ 3 = ?
84 ÷ 12 = ?
2 ÷ 2 = ?
72 ÷ 8 = ?
12 ÷ 3 = ?
Step 2 — cross out the sentence with each answer
1.The villain swipes a glowing coral tome, then escapes through a trench.
2.The villain grabs a heavy seashell dictionary, then slips into the dark abyss.
3.The villain snatches an ancient kelp map, then hides behind a school of tuna.
4.The villain grabs a heavy seashell dictionary, then escapes through a trench.
5.The villain snatches an ancient kelp map, then escapes through a trench.
6.The villain pockets a jellyfish journal, then zips away on a manta ray.
7.The villain steals a rare waterproof scroll, then hides behind a school of tuna.
8.The villain steals a rare waterproof scroll, then zips away on a manta ray.
9.The villain snatches an ancient kelp map, then zips away on a manta ray.
10.The villain steals a rare waterproof scroll, then swims past the barrier reef.
11.The villain swipes a glowing coral tome, then zips away on a manta ray.
12.The villain swipes a glowing coral tome, then swims past the barrier reef.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Golden Kelp
Culprit: Cindy Van Dover (Deep Sea Sonar · Diver Helmet · Writes Right Handed · Blue Diving Suit · Dried Krill Chips)
- Clue 1 (Fractions of a number): "THE THIEF DOES NOT CARRY THE ALGAE SATCHEL"2/3 of 33 = 22 (T) · 2/6 of 108 = 36 (C) · 1/4 of 128 = 32 (R) · 1/3 of 33 = 11 (A) · 1/3 of 30 = 10 (S) · 3/6 of 62 = 31 (O) · 1/2 of 50 = 25 (L) · 2/10 of 85 = 17 (N) · 4/5 of 25 = 20 (E) · 1/4 of 148 = 37 (F) · 1/5 of 45 = 9 (G) · 6/10 of 30 = 18 (I) · 1/2 of 70 = 35 (Y) · 3/6 of 28 = 14 (D) · 2/10 of 95 = 19 (H)
- Clue 2 (Order of operations): "WE SAW RIGHT HANDED SMUDGES ON THE COVER"11 × 6 - 19 = 47 (W) · 4 + 7 × 5 = 39 (O) · 3 + 4 × 2 = 11 (M) · 11 × 6 - 29 = 37 (E) · 18 + 2 × 4 = 26 (V) · 10 × 6 - 8 = 52 (A) · 9 × 9 - 12 = 69 (R) · 2 + 2 × 2 = 6 (T) · 40 + 5 × 3 = 55 (H) · 4 + 2 × 2 = 8 (U) · 18 + 9 × 2 = 36 (G) · 10 × 7 - 21 = 49 (C) · 9 × 10 - 17 = 73 (D) · 6 × 6 - 6 = 30 (S) · 5 × 7 - 1 = 34 (I) · 2 × 12 - 2 = 22 (N)
- Clue 3 (Multiplication facts (1-12)): "THE SCENE SMELLED OF DRIED KRILL CHIPS"11 × 5 = 55 (T) · 11 × 8 = 88 (F) · 9 × 9 = 81 (K) · 4 × 1 = 4 (R) · 11 × 6 = 66 (O) · 1 × 3 = 3 (D) · 4 × 4 = 16 (N) · 7 × 6 = 42 (E) · 4 × 7 = 28 (S) · 9 × 12 = 108 (L) · 11 × 11 = 121 (H) · 12 × 12 = 144 (C) · 9 × 11 = 99 (M) · 7 × 7 = 49 (I) · 2 × 1 = 2 (P)
- Clue 4 (Rounding): "THE ENEMY DROPPED A BLUE DIVING SUIT THREAD"Round 6,574 to the nearest thousand = 7000 (T) · Round 191 to the nearest hundred = 200 (B) · Round 4,521 to the nearest thousand = 5000 (E) · Round 128 to the nearest ten = 130 (P) · Round 3,652 to the nearest hundred = 3700 (O) · Round 49 to the nearest ten = 50 (D) · Round 226 to the nearest ten = 230 (V) · Round 368 to the nearest ten = 370 (N) · Round 4,288 to the nearest hundred = 4300 (S) · Round 114 to the nearest ten = 110 (I) · Round 746 to the nearest hundred = 700 (G) · Round 3,257 to the nearest thousand = 3000 (U) · Round 288 to the nearest ten = 290 (M) · Round 2,915 to the nearest hundred = 2900 (A) · Round 34 to the nearest ten = 30 (Y) · Round 540 to the nearest hundred = 500 (R) · Round 1,112 to the nearest hundred = 1100 (L) · Round 90 to the nearest ten = 90 (H)
- Clue 5 (Division facts (1-12)): surviving statement (box 8) → Cindy Van Dover108 ÷ 9 = 12 · 55 ÷ 11 = 5 · 20 ÷ 2 = 10 · 22 ÷ 2 = 11 · 6 ÷ 1 = 6 · 24 ÷ 8 = 3 · 6 ÷ 3 = 2 · 84 ÷ 12 = 7 · 2 ÷ 2 = 1 · 72 ÷ 8 = 9 · 12 ÷ 3 = 4
About this mystery
- Grade level
- Grade 5 math
- Math topics
- Fractions of a number, Order of operations, Multiplication, Rounding, Division
- Reading level
- grades 5-6
- Theme
- The Case of the Golden Kelp — set in The Great Coral Library
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects