Grade 8Reading: grades 7-9RoundingFractions of a numberBar modelsExponentsMissing addends
The Sunken Vault Sabotage
An unknown rogue sabotaged the deep-sea vault research lab and snatched the ancient abyssal artifact! Use your detective skills and decode the clues to identify the culprit before their submarine slips away into the 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 | Primary Gear | Secondary Gear | Dominant Hand | Hair Style | Defense Weapon |
|---|---|---|---|---|---|
| Captain Vance | grappling hook | mini drone | left handed | neon green braid | loud whistle |
| Crewman Ruby | stealth cloak | mini drone | left handed | spiked black mohawk | cold spray |
| Dr Elena | stealth cloak | shock shield | left handed | shaved silver buzz | loud whistle |
| Engineer Cora | stealth cloak | bio scanner | right handed | spiked black mohawk | cold spray |
| Crewman Jax | stealth cloak | anchor winch | right handed | shaved silver buzz | loud whistle |
| Engineer Maya | plasma cutter | anchor winch | right handed | neon green braid | cold spray |
| Captain Seth | sonic pulse | mini drone | right handed | neon green braid | loud whistle |
| Diver Hugo | grappling hook | bio scanner | right handed | shaved silver buzz | cold spray |
| Specialist Troy | stealth cloak | anchor winch | right handed | neon green braid | cold spray |
| Diver Leah | stealth cloak | mini drone | right handed | spiked black mohawk | cold spray |
| Tech Nora | jet booster | thermal flare | right handed | shaved silver buzz | loud whistle |
| Specialist Leo | plasma cutter | mini drone | right handed | spiked black mohawk | cold spray |
| Specialist Zane | sonic pulse | thermal flare | right handed | spiked black mohawk | cold spray |
| Pilot Kai | jet booster | shock shield | right handed | neon green braid | loud whistle |
| Cadet Liam | grappling hook | shock shield | left handed | shaved silver buzz | loud whistle |
| Pilot Owen | stealth cloak | thermal flare | right handed | shaved silver buzz | loud whistle |
| Officer Bryce | jet booster | anchor winch | right handed | shaved silver buzz | loud whistle |
| Officer Clara | stealth cloak | bio scanner | right handed | neon green braid | loud whistle |
| Officer Nina | sonic pulse | shock shield | right handed | spiked black mohawk | cold spray |
| Tech Ezra | grappling hook | thermal flare | right handed | neon green braid | bright flash |
| Diver Ross | sonic pulse | mini drone | right handed | spiked black mohawk | loud whistle |
Clue 1
Rounding
The sonar terminal only displays distance measurements rounded to the nearest ten meters.
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
20
500
130
50
2000
1100
1100
2900
2000
70
200
700
130
3000
70
700
T
20
2300
3000
130
2900
T
20
500
130
300
1700
2900
1100
5000
1100
2900
300
130
Round 21 to the nearest tenT
Round 2,086 to the nearest thousandI
Round 128 to the nearest tenE
Round 1,734 to the nearest hundredM
Round 1,149 to the nearest hundredL
Round 2,308 to the nearest hundredU
Round 471 to the nearest hundredH
Round 50 to the nearest tenV
Round 738 to the nearest hundredO
Round 2,857 to the nearest hundredA
Round 3,211 to the nearest thousandS
Round 69 to the nearest tenN
Round 191 to the nearest hundredD
Round 300 to the nearest hundredR
Round 4,521 to the nearest thousandF
0/15 letters found
Clue 2
Fractions of a number
To open the emergency hatch, you must calculate the fractional fuel ratio needed for the backup engine.
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
24
46
28
29
23
23
23
37
W
47
37
38
24
8
2
46
2
37
28
57
29
57
49
39
29
38
37
46
49
38
1/3 of 141 =W
1/2 of 4 =H
7/8 of 56 =O
1/2 of 92 =T
3/6 of 74 =A
4/8 of 114 =D
1/5 of 145 =E
2/3 of 12 =G
1/2 of 48 =I
3/6 of 46 =S
7/8 of 32 =N
2/8 of 152 =R
3/4 of 52 =P
0/13 letters found
Clue 3
Bar model word problems
The energy grid balance board compares total power bars across the submarine sectors.
Draw a bar model to solve each word problem. Its answer reveals a letter — write the letters in the boxes to fill in the missing word.
Someonescaredthevillainoffwith .
C
81
16
85
17
24
89
29
A
Y
Submarine Navigator has 162 repair kits, packed 2 to a bag. How many bags can be filled?
draw a bar model
Answer:→C
One group collected 10 depth gauges and another group collected 7 depth gauges. How many depth gauges in all?
draw a bar model
Answer:→D
Submarine Navigator has 2 times as many depth gauges as a teammate. The teammate has 12 depth gauges. How many depth gauges does Submarine Navigator have?
draw a bar model
Answer:→S
There were 40 sonar beacons in all. 24 sonar beacons were used. How many sonar beacons are left?
draw a bar model
Answer:→O
Submarine Navigator used 2/5 of the pressure valves on the first day. The other 51 pressure valves were used the next day. How many pressure valves were there in all?
draw a bar model
Answer:→L
Submarine Navigator has 145 sonar beacons, packed 5 to a bag. How many bags can be filled?
draw a bar model
Answer:→R
Submarine Navigator shares 178 repair kits equally among 2 teams. How many repair kits does each team get?
draw a bar model
Answer:→P
0/7 letters found
Clue 4
Exponents
Analyzing the exponential growth pattern of the vault alarm signal reveals key coordinates.
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
9
625
128
169
324
225
289
27
32
4
729
324
16
121
225
400
4
125
625
49
225
343
4
225
81
289
400
729
169
729
3^2 =F
7^3 =W
9^3 =E
2^5 =I
2^4 =B
18^2 =D
2^7 =U
11^2 =L
3^3 =P
20^2 =C
17^2 =S
2^2 =K
5^3 =M
5^4 =O
7^2 =H
3^4 =T
15^2 =A
13^2 =N
0/18 letters found
Clue 5
Missing addends — the last clue
The pressure valve control requires finding the missing total force to stabilize the airlock.
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
34 + ___ = 42
31 + ___ = 40
16 + ___ = 20
1 + ___ = 4
6 + ___ = 7
14 + ___ = 24
26 + ___ = 37
29 + ___ = 34
10 + ___ = 16
4 + ___ = 16
22 + ___ = 24
Step 2 — cross out the sentence with each answer
1.The villain sliced through with a plasma cutter, then deployed a thermal flare.
2.The villain blasted off with a jet booster, then deployed a thermal flare.
3.The villain activated a sonic pulse, then scanned with a bio scanner.
4.The villain vanished using a stealth cloak, then scanned with a bio scanner.
5.The villain activated a sonic pulse, then launched a mini drone.
6.The villain fired a grappling hook, then scanned with a bio scanner.
7.The villain activated a sonic pulse, then raised a shock shield.
8.The villain sliced through with a plasma cutter, then launched a mini drone.
9.The villain vanished using a stealth cloak, then launched a mini drone.
10.The villain vanished using a stealth cloak, then wound up an anchor winch.
11.The villain fired a grappling hook, then launched a mini drone.
12.The villain vanished using a stealth cloak, then raised a shock shield.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Sunken Vault Sabotage
Culprit: Officer Nina (sonic pulse · shock shield · right handed · spiked black mohawk · cold spray)
- Clue 1 (Rounding): "THE VILLAIN DOES NOT USE A THERMAL FLARE"Round 21 to the nearest ten = 20 (T) · Round 2,086 to the nearest thousand = 2000 (I) · Round 128 to the nearest ten = 130 (E) · Round 1,734 to the nearest hundred = 1700 (M) · Round 1,149 to the nearest hundred = 1100 (L) · Round 2,308 to the nearest hundred = 2300 (U) · Round 471 to the nearest hundred = 500 (H) · Round 50 to the nearest ten = 50 (V) · Round 738 to the nearest hundred = 700 (O) · Round 2,857 to the nearest hundred = 2900 (A) · Round 3,211 to the nearest thousand = 3000 (S) · Round 69 to the nearest ten = 70 (N) · Round 191 to the nearest hundred = 200 (D) · Round 300 to the nearest hundred = 300 (R) · Round 4,521 to the nearest thousand = 5000 (F)
- Clue 2 (Fractions of a number): "WITNESS SAW A RIGHT HANDED OPERATOR"1/3 of 141 = 47 (W) · 1/2 of 4 = 2 (H) · 7/8 of 56 = 49 (O) · 1/2 of 92 = 46 (T) · 3/6 of 74 = 37 (A) · 4/8 of 114 = 57 (D) · 1/5 of 145 = 29 (E) · 2/3 of 12 = 8 (G) · 1/2 of 48 = 24 (I) · 3/6 of 46 = 23 (S) · 7/8 of 32 = 28 (N) · 2/8 of 152 = 38 (R) · 3/4 of 52 = 39 (P)
- Clue 3 (Bar model word problems): "COLD SPRAY"Submarine Navigator has 162 repair kits, packed 2 to a bag. How many bags can be filled? = 81 (C) · One group collected 10 depth gauges and another group collected 7 depth gauges. How many depth gauges in all? = 17 (D) · Submarine Navigator has 2 times as many depth gauges as a teammate. The teammate has 12 depth gauges. How many depth gauges does Submarine Navigator have? = 24 (S) · There were 40 sonar beacons in all. 24 sonar beacons were used. How many sonar beacons are left? = 16 (O) · Submarine Navigator used 2/5 of the pressure valves on the first day. The other 51 pressure valves were used the next day. How many pressure valves were there in all? = 85 (L) · Submarine Navigator has 145 sonar beacons, packed 5 to a bag. How many bags can be filled? = 29 (R) · Submarine Navigator shares 178 repair kits equally among 2 teams. How many repair kits does each team get? = 89 (P)
- Clue 4 (Exponents): "FOUND A SPIKED BLACK MOHAWK AT SCENE"3^2 = 9 (F) · 7^3 = 343 (W) · 9^3 = 729 (E) · 2^5 = 32 (I) · 2^4 = 16 (B) · 18^2 = 324 (D) · 2^7 = 128 (U) · 11^2 = 121 (L) · 3^3 = 27 (P) · 20^2 = 400 (C) · 17^2 = 289 (S) · 2^2 = 4 (K) · 5^3 = 125 (M) · 5^4 = 625 (O) · 7^2 = 49 (H) · 3^4 = 81 (T) · 15^2 = 225 (A) · 13^2 = 169 (N)
- Clue 5 (Missing addends): surviving statement (box 7) → Officer Nina34 + ___ = 42 = 8 · 31 + ___ = 40 = 9 · 16 + ___ = 20 = 4 · 1 + ___ = 4 = 3 · 6 + ___ = 7 = 1 · 14 + ___ = 24 = 10 · 26 + ___ = 37 = 11 · 29 + ___ = 34 = 5 · 10 + ___ = 16 = 6 · 4 + ___ = 16 = 12 · 22 + ___ = 24 = 2
About this mystery
- Grade level
- Grade 8 math
- Math topics
- Rounding, Fractions of a number, Bar models, Exponents, Missing addends
- Reading level
- grades 7-9
- Theme
- The Sunken Vault Sabotage — set in The Nautilus Submarine Station
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects