🌊 OceanGrade 7Reading: grades 7-9MultiplicationWord problemsFractions of a numberMulti-step word problems
The Abyssal Reef Heist
A daring saboteur has breached the high-tech underwater labs of the Sunken Reef Research Station! The primary energy core has been taken, and the marine sanctuary is losing power. We must analyze the physical evidence and use tactical mathematics to identify the culprit before they escape into the open ocean.
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 | Deep Sea Gear | Infiltration Device | Observed Device placement | Stray Hair Sample | Countermeasure Strategy |
|---|---|---|---|---|---|
| Jacques Cousteau | hydro-jet thrusters | thermal engine boost | wears a right-wrist sonar | shimmering silver hair | sticky sea-foam spray |
| Charles Darwin | laser glass cutter | black ink smoke-screen | wears a left-wrist sonar | kelp green hair | sticky sea-foam spray |
| Edith Widder | mechanical claw | chameleon kelp camo | wears a right-wrist sonar | shimmering silver hair | loud high-frequency ping |
| Ernest Shackleton | hydro-jet thrusters | thermal engine boost | wears a left-wrist sonar | neon coral hair | loud high-frequency ping |
| Fridtjof Nansen | hydro-jet thrusters | high-voltage eel shock | wears a right-wrist sonar | neon coral hair | bright high-beam flash |
| James Cameron | heavy depth armor | magnetic anchor lock | wears a right-wrist sonar | kelp green hair | sticky sea-foam spray |
| Sylvia Earle | sonar tracking system | high-voltage eel shock | wears a right-wrist sonar | shimmering silver hair | sticky sea-foam spray |
| Robert Ballard | hydro-jet thrusters | thermal engine boost | wears a right-wrist sonar | kelp green hair | sticky sea-foam spray |
| Alistair Hardy | sonar tracking system | high-voltage eel shock | wears a right-wrist sonar | kelp green hair | sticky sea-foam spray |
| Rachel Carson | laser glass cutter | chameleon kelp camo | wears a left-wrist sonar | neon coral hair | sticky sea-foam spray |
| Matthew Henson | sonar tracking system | magnetic anchor lock | wears a right-wrist sonar | kelp green hair | sticky sea-foam spray |
| Walter Munk | laser glass cutter | high-voltage eel shock | wears a left-wrist sonar | kelp green hair | bright high-beam flash |
| Jeanne Baret | sonar tracking system | magnetic anchor lock | wears a left-wrist sonar | neon coral hair | loud high-frequency ping |
| Vilhjalmur Stefansson | hydro-jet thrusters | high-voltage eel shock | wears a left-wrist sonar | neon coral hair | sticky sea-foam spray |
| James Cook | hydro-jet thrusters | chameleon kelp camo | wears a right-wrist sonar | kelp green hair | sticky sea-foam spray |
| Eugenie Clark | heavy depth armor | black ink smoke-screen | wears a right-wrist sonar | shimmering silver hair | sticky sea-foam spray |
| William Beebe | mechanical claw | black ink smoke-screen | wears a right-wrist sonar | kelp green hair | bright high-beam flash |
| Vasco da Gama | heavy depth armor | magnetic anchor lock | wears a right-wrist sonar | kelp green hair | loud high-frequency ping |
| John Cabot | heavy depth armor | thermal engine boost | wears a right-wrist sonar | kelp green hair | loud high-frequency ping |
| Roger Revelle | laser glass cutter | chameleon kelp camo | wears a left-wrist sonar | shimmering silver hair | bright high-beam flash |
| Auguste Piccard | mechanical claw | black ink smoke-screen | wears a right-wrist sonar | neon coral hair | bright high-beam flash |
Clue 1
Multiplication facts (1-12)
The salvage crew finds several storage racks inside the flooded chamber, each containing a grid of gear boxes. Multiply the rows of gear by the columns to count the total kits and recover the first encoded 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
16
132
9
108
10
12
121
33
1
35
9
108
70
35
T
16
8
108
9
10
132
12
121
9
54
9
35
70
30
9
54
33
10
12
121
35
2 × 8 =T
1 × 8 =U
11 × 11 =M
10 × 7 =N
5 × 6 =K
6 × 9 =L
11 × 3 =P
9 × 1 =E
11 × 12 =H
9 × 12 =S
7 × 5 =O
10 × 1 =C
2 × 6 =A
1 × 1 =D
0/14 letters found
Clue 2
Word problems
We intercept a scrambled acoustic signal bouncing off the deep ocean trench. Deciphering the sonar logs reveals a word puzzle about supply distributions that unlocks the second lead.
Solve each problem to learn its letter, then write the letters in the boxes to fill in the missing word.
Awitnesssawthevillainwas .
W
80
18
57
56
34
57
56
110
66
H
T
W
80
56
110
34
T
34
O
N
57
56
There were 99 pearl clams. 19 were used up. How many pearl clams are left?W
There were 44 coral samples. 26 were used up. How many coral samples are left?E
There were 68 diving tanks. 11 were used up. How many diving tanks are left?A
The marine biologist found 15 coral samples yesterday and 41 more today. How many coral samples in all?R
The marine biologist found 11 pearl clams yesterday and 23 more today. How many pearl clams in all?S
The marine biologist lined up 10 rows of 11 diving tanks. How many diving tanks in all?I
The marine biologist lined up 6 rows of 11 coral samples. How many coral samples in all?G
0/7 letters found
Clue 3
Fractions of a number
A locked copper trunk from the sunken wreck requires a fraction of the gold coins to be placed on a pressure plate. Calculating this exact fraction pops open the double latch.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
U
31
53
55
37
15
55
53
37
13
46
56
11
53
55
52
26
8
52
51
53
19
42
52
11
8
3
37
15
55
51
1/2 of 62 =U
3/6 of 52 =F
3/6 of 74 =T
2/4 of 106 =S
4/8 of 102 =M
3/5 of 70 =R
1/2 of 16 =O
5/10 of 110 =E
4/10 of 130 =A
1/8 of 104 =I
4/6 of 69 =C
1/8 of 152 =P
3/4 of 20 =H
1/4 of 12 =N
1/3 of 168 =K
3/6 of 22 =Y
0/16 letters found
Clue 4
Multi-step word problems
Our submarine needs to balance its fuel tanks and ballast weight before descending into the abyss. Solving the multi-step load calculations allows the main computer to scan the seafloor.
Solve each problem to learn its letter, then write the letters in the boxes to fill in the missing word.
Astrandof hairturnedupatthescene.
K
89
9
19
46
7
90
9
9
25
H
A
I
90
The marine biologist filled 4 boxes with 6 diving tanks each, then found 65 more diving tanks. How many diving tanks are there in all?K
The marine biologist collected 31 lead anchors in the morning and 14 lead anchors in the afternoon, then split them equally among 5 the research vessel crew. How many lead anchors did each get?E
There were 358 lead anchors in all. 36 lead anchors were set aside. The rest were shared equally among 7 the research vessel crew. How many lead anchors did each get?P
The marine biologist collected 117 lead anchors in the morning and 153 lead anchors in the afternoon, then split them equally among 3 the research vessel crew. How many lead anchors did each get?R
The marine biologist collected 29 diving tanks in the morning and 13 diving tanks in the afternoon, then split them equally among 6 the research vessel crew. How many diving tanks did each get?G
The marine biologist earned 6 pearl clams in each of 2 rounds, plus 21 bonus pearl clams. Then 8 pearl clams were lost. How many pearl clams are left?N
The marine biologist collected 19 diving tanks in the morning and 38 diving tanks in the afternoon, then split them equally among 3 the research vessel crew. How many diving tanks did each get?L
0/7 letters found
Clue 5
Fractions of a number — the last clue
The pressure-dome vault is sealed by a water-wheel lock. We must drain a precise fraction of the total gallons in the main tank to stop the gears and grab the final piece of evidence.
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
2/6 of 36 = ?
1/5 of 10 = ?
2/8 of 28 = ?
1/8 of 32 = ?
2/4 of 2 = ?
2/8 of 20 = ?
1/10 of 30 = ?
3/10 of 20 = ?
8/10 of 10 = ?
1/5 of 55 = ?
4/8 of 18 = ?
Step 2 — cross out the sentence with each answer
1.The villain sabotaged the sub's propellers, then hid in the dark trenches.
2.The villain cracked open the deep sea vault, then fled into the sunken shipwreck.
3.The villain stole the giant pearl of the reef, then slipped away through the kelp forest.
4.The villain reprogrammed the research drone, then swam off into the barrier reef.
5.The villain disabled the underwater habitat generator, then hid in the dark trenches.
6.The villain sabotaged the sub's propellers, then fled into the sunken shipwreck.
7.The villain stole the giant pearl of the reef, then escaped in a swift mini-sub.
8.The villain cracked open the deep sea vault, then swam off into the barrier reef.
9.The villain disabled the underwater habitat generator, then escaped in a swift mini-sub.
10.The villain sabotaged the sub's propellers, then slipped away through the kelp forest.
11.The villain reprogrammed the research drone, then escaped in a swift mini-sub.
12.The villain stole the giant pearl of the reef, then fled into the sunken shipwreck.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Abyssal Reef Heist
Culprit: Robert Ballard (hydro-jet thrusters · thermal engine boost · wears a right-wrist sonar · kelp green hair · sticky sea-foam spray)
- Clue 1 (Multiplication facts (1-12)): "THE SCAMP DOES NOT USE CHAMELEON KELP CAMO"2 × 8 = 16 (T) · 1 × 8 = 8 (U) · 11 × 11 = 121 (M) · 10 × 7 = 70 (N) · 5 × 6 = 30 (K) · 6 × 9 = 54 (L) · 11 × 3 = 33 (P) · 9 × 1 = 9 (E) · 11 × 12 = 132 (H) · 9 × 12 = 108 (S) · 7 × 5 = 35 (O) · 10 × 1 = 10 (C) · 2 × 6 = 12 (A) · 1 × 1 = 1 (D)
- Clue 2 (Word problems): "WEARS A RIGHT WRIST SONAR"There were 99 pearl clams. 19 were used up. How many pearl clams are left? = 80 (W) · There were 44 coral samples. 26 were used up. How many coral samples are left? = 18 (E) · There were 68 diving tanks. 11 were used up. How many diving tanks are left? = 57 (A) · The marine biologist found 15 coral samples yesterday and 41 more today. How many coral samples in all? = 56 (R) · The marine biologist found 11 pearl clams yesterday and 23 more today. How many pearl clams in all? = 34 (S) · The marine biologist lined up 10 rows of 11 diving tanks. How many diving tanks in all? = 110 (I) · The marine biologist lined up 6 rows of 11 coral samples. How many coral samples in all? = 66 (G)
- Clue 3 (Fractions of a number): "USE THE STICKY SEA FOAM SPRAY ON THEM"1/2 of 62 = 31 (U) · 3/6 of 52 = 26 (F) · 3/6 of 74 = 37 (T) · 2/4 of 106 = 53 (S) · 4/8 of 102 = 51 (M) · 3/5 of 70 = 42 (R) · 1/2 of 16 = 8 (O) · 5/10 of 110 = 55 (E) · 4/10 of 130 = 52 (A) · 1/8 of 104 = 13 (I) · 4/6 of 69 = 46 (C) · 1/8 of 152 = 19 (P) · 3/4 of 20 = 15 (H) · 1/4 of 12 = 3 (N) · 1/3 of 168 = 56 (K) · 3/6 of 22 = 11 (Y)
- Clue 4 (Multi-step word problems): "KELP GREEN HAIR"The marine biologist filled 4 boxes with 6 diving tanks each, then found 65 more diving tanks. How many diving tanks are there in all? = 89 (K) · The marine biologist collected 31 lead anchors in the morning and 14 lead anchors in the afternoon, then split them equally among 5 the research vessel crew. How many lead anchors did each get? = 9 (E) · There were 358 lead anchors in all. 36 lead anchors were set aside. The rest were shared equally among 7 the research vessel crew. How many lead anchors did each get? = 46 (P) · The marine biologist collected 117 lead anchors in the morning and 153 lead anchors in the afternoon, then split them equally among 3 the research vessel crew. How many lead anchors did each get? = 90 (R) · The marine biologist collected 29 diving tanks in the morning and 13 diving tanks in the afternoon, then split them equally among 6 the research vessel crew. How many diving tanks did each get? = 7 (G) · The marine biologist earned 6 pearl clams in each of 2 rounds, plus 21 bonus pearl clams. Then 8 pearl clams were lost. How many pearl clams are left? = 25 (N) · The marine biologist collected 19 diving tanks in the morning and 38 diving tanks in the afternoon, then split them equally among 3 the research vessel crew. How many diving tanks did each get? = 19 (L)
- Clue 5 (Fractions of a number): surviving statement (box 10) → Robert Ballard2/6 of 36 = 12 · 1/5 of 10 = 2 · 2/8 of 28 = 7 · 1/8 of 32 = 4 · 2/4 of 2 = 1 · 2/8 of 20 = 5 · 1/10 of 30 = 3 · 3/10 of 20 = 6 · 8/10 of 10 = 8 · 1/5 of 55 = 11 · 4/8 of 18 = 9
About this mystery
- Grade level
- Grade 7 math
- Math topics
- Multiplication, Word problems, Fractions of a number, Multi-step word problems
- Reading level
- grades 7-9
- Theme
- The Abyssal Reef Heist — set in The Sunken Reef Research Station
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects