Grade 5Reading: grades 5-6MultiplicationFractions of a numberOrder of operationsRoundingDivision
The Case of the Sunken Beacon
A rogue diver sabotaged the main underwater beacon at Sapphire Cove! Detective, examine the gear logs and unmask the culprit before the storm arrives.
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 | Diving Gear | Specialty Tool | Dominant Hand | Headgear | Defense Weakness |
|---|---|---|---|---|---|
| Diver Sam | Anchor Blasters | Laser Cutter | Left Handed | Bare Head | Magnetic Clamps |
| Diver Paige | Grapple Hooks | Bubble Shield | Left Handed | Neoprene Hood | High Pitch Whistles |
| Analyst Iris | Thermal Suits | Laser Cutter | Right Handed | Bare Head | High Pitch Whistles |
| Dr Marina Cruz | Thermal Suits | Decoy Flare | Left Handed | Diving Cap | Bright Flashlights |
| Tech Maya | Thermal Suits | Net Launcher | Right Handed | Neoprene Hood | Magnetic Clamps |
| Captain Vance | Sonic Sonar | Bubble Shield | Left Handed | Bare Head | High Pitch Whistles |
| Engineer Leo | Sonic Sonar | Decoy Flare | Left Handed | Neoprene Hood | Magnetic Clamps |
| Professor Seth | Anchor Blasters | Sea Glider | Right Handed | Bare Head | Bright Flashlights |
| Specialist Eli | Grapple Hooks | Decoy Flare | Left Handed | Diving Cap | High Pitch Whistles |
| Officer Jade | Anchor Blasters | Sea Glider | Right Handed | Bare Head | High Pitch Whistles |
| Sub Master Kai | Grapple Hooks | Bubble Shield | Left Handed | Diving Cap | Bright Flashlights |
| Explorer Nora | Thermal Suits | Decoy Flare | Left Handed | Neoprene Hood | Bright Flashlights |
| Pilot Cole | Thermal Suits | Sea Glider | Left Handed | Diving Cap | High Pitch Whistles |
| Scuba Liam | Plasma Torches | Net Launcher | Left Handed | Diving Cap | Bright Flashlights |
| Officer Blake | Plasma Torches | Decoy Flare | Left Handed | Diving Cap | Bright Flashlights |
| Navigator Tess | Grapple Hooks | Laser Cutter | Left Handed | Diving Cap | Bright Flashlights |
| Mechanic Wade | Anchor Blasters | Laser Cutter | Left Handed | Diving Cap | High Pitch Whistles |
| Pilot Jax | Plasma Torches | Laser Cutter | Left Handed | Bare Head | High Pitch Whistles |
| Commander Reed | Plasma Torches | Sea Glider | Left Handed | Neoprene Hood | Bright Flashlights |
| Researcher Finn | Thermal Suits | Bubble Shield | Right Handed | Diving Cap | Bright Flashlights |
| Operator Tara | Anchor Blasters | Net Launcher | Left Handed | Neoprene Hood | Bright Flashlights |
Clue 1
Multiplication facts (1-12)
To check the sonar grid, the team counts rows of underwater sensors.
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
81
64
72
121
120
3
44
27
T
14
6
70
64
144
54
70
T
14
121
144
64
10
54
64
T
14
120
10
121
54
72
81
64
44
7 × 2 =T
10 × 12 =L
3 × 9 =I
9 × 6 =N
3 × 2 =D
1 × 10 =A
8 × 9 =C
11 × 11 =U
4 × 11 =R
7 × 10 =O
12 × 12 =S
9 × 9 =H
1 × 3 =P
8 × 8 =E
0/14 letters found
Clue 2
Fractions of a number
The submarine manager reviews a fraction of the fuel logs from the morning dive.
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
30
26
19
29
17
12
12
12
3
W
30
14
17
13
19
38
3
29
22
17
22
4
6
26
9
8
29
14
17
32
17
6
1/2 of 60 =W
1/10 of 140 =L
2/10 of 65 =F
3/10 of 20 =R
4/10 of 95 =H
1/6 of 24 =G
8/10 of 10 =O
2/10 of 160 =V
4/6 of 33 =D
4/8 of 58 =N
3/5 of 20 =S
1/5 of 95 =T
4/10 of 65 =I
1/10 of 90 =P
1/6 of 18 =A
2/4 of 34 =E
0/16 letters found
Clue 3
Order of operations
Following a multi step safety sequence, the crew calculates total station voltage.
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
18
56
47
45
62
T
18
64
56
12
70
8
48
37
15
62
15
70
46
70
47
48
45
33
T
18
32
8
56
12
33
8
48
45
33
T
18
12
12 × 4 - 30 =T
15 + 6 × 3 =H
7 × 9 - 7 =A
58 + 6 × 2 =B
11 + 2 × 2 =D
12 × 6 - 25 =R
7 × 6 - 5 =N
32 + 7 × 2 =Y
4 + 2 × 2 =L
7 × 12 - 20 =W
29 + 8 × 2 =G
10 × 6 - 12 =I
3 + 3 × 3 =S
7 × 6 - 10 =F
8 × 9 - 10 =E
0/15 letters found
Clue 4
Rounding
The station radar screen only displays rounded depth readings.
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
300
1700
9000
230
9000
1100
130
200
1700
130
9000
500
9000
1100
900
9000
50
1100
50
130
5000
2000
2000
9000
50
50
290
500
290
1300
20
200
1100
2000
Round 348 to the nearest hundredT
Round 20 to the nearest tenG
Round 132 to the nearest tenR
Round 917 to the nearest hundredL
Round 4,736 to the nearest thousandO
Round 546 to the nearest hundredV
Round 1,291 to the nearest hundredN
Round 54 to the nearest tenD
Round 246 to the nearest hundredC
Round 2,310 to the nearest thousandP
Round 292 to the nearest tenI
Round 1,077 to the nearest hundredA
Round 1,669 to the nearest hundredH
Round 230 to the nearest tenS
Round 9,442 to the nearest thousandE
0/15 letters found
Clue 5
Division facts (1-12) — the last clue
The divers split the remaining air canisters equally across teams.
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
28 ÷ 4 = ?
40 ÷ 5 = ?
70 ÷ 7 = ?
63 ÷ 7 = ?
11 ÷ 1 = ?
72 ÷ 12 = ?
7 ÷ 7 = ?
27 ÷ 9 = ?
18 ÷ 9 = ?
20 ÷ 5 = ?
35 ÷ 7 = ?
Step 2 — cross out the sentence with each answer
1.The villain welded the hatch shut, then sliced open the emergency tank.
2.The villain disabled the thermal suit power, then tangled the research lines.
3.The villain disabled the thermal suit power, then deflected the security sensors.
4.The villain disabled the thermal suit power, then zoomed away on a scooter.
5.The villain jammed the sonar array, then sliced open the emergency tank.
6.The villain cut the anchor cables, then launched a distracting signal.
7.The villain disabled the thermal suit power, then launched a distracting signal.
8.The villain snapped the winch ropes, then sliced open the emergency tank.
9.The villain cut the anchor cables, then zoomed away on a scooter.
10.The villain welded the hatch shut, then launched a distracting signal.
11.The villain jammed the sonar array, then tangled the research lines.
12.The villain snapped the winch ropes, then deflected the security sensors.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Sunken Beacon
Culprit: Sub Master Kai (Grapple Hooks · Bubble Shield · Left Handed · Diving Cap · Bright Flashlights)
- Clue 1 (Multiplication facts (1-12)): "THE CULPRIT DOES NOT USE A NET LAUNCHER"7 × 2 = 14 (T) · 10 × 12 = 120 (L) · 3 × 9 = 27 (I) · 9 × 6 = 54 (N) · 3 × 2 = 6 (D) · 1 × 10 = 10 (A) · 8 × 9 = 72 (C) · 11 × 11 = 121 (U) · 4 × 11 = 44 (R) · 7 × 10 = 70 (O) · 12 × 12 = 144 (S) · 9 × 9 = 81 (H) · 1 × 3 = 3 (P) · 8 × 8 = 64 (E)
- Clue 2 (Fractions of a number): "WITNESS SAW LEFT HANDED GRIP ON LEVER"1/2 of 60 = 30 (W) · 1/10 of 140 = 14 (L) · 2/10 of 65 = 13 (F) · 3/10 of 20 = 6 (R) · 4/10 of 95 = 38 (H) · 1/6 of 24 = 4 (G) · 8/10 of 10 = 8 (O) · 2/10 of 160 = 32 (V) · 4/6 of 33 = 22 (D) · 4/8 of 58 = 29 (N) · 3/5 of 20 = 12 (S) · 1/5 of 95 = 19 (T) · 4/10 of 65 = 26 (I) · 1/10 of 90 = 9 (P) · 1/6 of 18 = 3 (A) · 2/4 of 34 = 17 (E)
- Clue 3 (Order of operations): "TARGET WAS BLINDED BY BRIGHT FLASHLIGHTS"12 × 4 - 30 = 18 (T) · 15 + 6 × 3 = 33 (H) · 7 × 9 - 7 = 56 (A) · 58 + 6 × 2 = 70 (B) · 11 + 2 × 2 = 15 (D) · 12 × 6 - 25 = 47 (R) · 7 × 6 - 5 = 37 (N) · 32 + 7 × 2 = 46 (Y) · 4 + 2 × 2 = 8 (L) · 7 × 12 - 20 = 64 (W) · 29 + 8 × 2 = 45 (G) · 10 × 6 - 12 = 48 (I) · 3 + 3 × 3 = 12 (S) · 7 × 6 - 10 = 32 (F) · 8 × 9 - 10 = 62 (E)
- Clue 4 (Rounding): "THE SEARCH REVEALED A DROPPED DIVING CAP"Round 348 to the nearest hundred = 300 (T) · Round 20 to the nearest ten = 20 (G) · Round 132 to the nearest ten = 130 (R) · Round 917 to the nearest hundred = 900 (L) · Round 4,736 to the nearest thousand = 5000 (O) · Round 546 to the nearest hundred = 500 (V) · Round 1,291 to the nearest hundred = 1300 (N) · Round 54 to the nearest ten = 50 (D) · Round 246 to the nearest hundred = 200 (C) · Round 2,310 to the nearest thousand = 2000 (P) · Round 292 to the nearest ten = 290 (I) · Round 1,077 to the nearest hundred = 1100 (A) · Round 1,669 to the nearest hundred = 1700 (H) · Round 230 to the nearest ten = 230 (S) · Round 9,442 to the nearest thousand = 9000 (E)
- Clue 5 (Division facts (1-12)): surviving statement (box 12) → Sub Master Kai28 ÷ 4 = 7 · 40 ÷ 5 = 8 · 70 ÷ 7 = 10 · 63 ÷ 7 = 9 · 11 ÷ 1 = 11 · 72 ÷ 12 = 6 · 7 ÷ 7 = 1 · 27 ÷ 9 = 3 · 18 ÷ 9 = 2 · 20 ÷ 5 = 4 · 35 ÷ 7 = 5
About this mystery
- Grade level
- Grade 5 math
- Math topics
- Multiplication, Fractions of a number, Order of operations, Rounding, Division
- Reading level
- grades 5-6
- Theme
- The Case of the Sunken Beacon — set in Sapphire Cove Research Station
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects