🤖 RobotsGrade 2Reading: grades 1-2AdditionPlace valueSubtractionSkip countingMissing addends
The Spark Yard Mystery
Someone snuck into the Spark Yard and took the Golden Gear! We must find the scrap thief before the city runs out of power. Look at the robot files to find the 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 | Tool Power | Backpack Gear | Oil Leak | Head Topper | System Reset |
|---|---|---|---|---|---|
| Byte | drill nose | search light | left side leak | silver dome | water splash |
| Turbo | drill nose | solar panel | left side leak | silver dome | rust spray |
| Gearbox | jet booster | search light | left side leak | glass bulb | rust spray |
| Sparky | jet booster | bubble fan | left side leak | glass bulb | rust spray |
| Sprocket | laser cutter | robo alarm | left side leak | glass bulb | rust spray |
| Clank | jet booster | bubble fan | right side leak | silver dome | magnet wave |
| Charger | drill nose | bubble fan | left side leak | glass bulb | rust spray |
| Widget | sonar ear | solar panel | left side leak | glass bulb | magnet wave |
| Otto | magnet claw | bubble fan | right side leak | silver dome | water splash |
| Astro | sonar ear | robo alarm | left side leak | glass bulb | magnet wave |
| Gasket | sonar ear | robo alarm | right side leak | glass bulb | magnet wave |
| Micro | sonar ear | robo alarm | right side leak | glass bulb | rust spray |
| Rivet | jet booster | smoke pipe | right side leak | glass bulb | rust spray |
| Tinny | laser cutter | solar panel | left side leak | glass bulb | rust spray |
| Copper | drill nose | robo alarm | right side leak | silver dome | rust spray |
| Beep | magnet claw | smoke pipe | left side leak | glass bulb | rust spray |
| Gizmo | drill nose | robo alarm | left side leak | spinning fan | rust spray |
| Dynamo | magnet claw | bubble fan | right side leak | spinning fan | rust spray |
| Rusty | drill nose | robo alarm | left side leak | spinning fan | magnet wave |
| Vector | sonar ear | smoke pipe | right side leak | spinning fan | water splash |
| Bolt | sonar ear | bubble fan | right side leak | glass bulb | magnet wave |
Clue 1
Addition
We need to count the fallen nuts and bolts on the floor. Let us add them together to unlock the first video clip.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
N
55
30
76
86
76
76
59
69
64
63
N
55
30
N
55
57
37
69
57
37
40
69
64
38 + 17 =N
50 + 36 =U
25 + 12 =H
33 + 36 =E
30 + 33 =A
39 + 20 =L
23 + 17 =I
21 + 9 =O
32 + 25 =T
30 + 34 =F
42 + 34 =B
0/11 letters found
Clue 2
Place value
Look at the digital screen on the main robot charger. We can read the tens and ones to unlock the secret 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.
A
17
77
28
46
12
57
13
A
17
46
12
12
20
A
17
33
82
57
28
57
39
20
12
20
84
57
What number has 1 ten and 7 ones?A
What number has 1 ten and 3 ones?R
What number has 8 tens and 2 ones?S
What number has 3 tens and 3 ones?D
What number has 2 tens and 0 ones?E
What number has 7 tens and 7 ones?N
What number has 8 tens and 4 ones?F
What number has 3 tens and 9 ones?H
What number has 5 tens and 7 ones?T
What number has 4 tens and 6 ones?I
What number has 1 ten and 2 ones?L
What number has 2 tens and 8 ones?O
0/12 letters found
Clue 3
Subtraction
Some battery packs are missing from the charging rack. Subtract the old count from the new count to find the difference.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
R
74
83
25
68
25
46
R
74
43
11
32
40
24
24
58
R
74
87
87
20
87
68
23
87
25
11
25
68
87
86
79 - 5 =R
67 - 35 =W
62 - 19 =A
46 - 22 =L
57 - 37 =Z
124 - 37 =E
55 - 15 =I
85 - 2 =U
48 - 2 =P
102 - 16 =M
24 - 13 =Y
53 - 30 =H
58 - 33 =S
63 - 5 =F
78 - 10 =T
0/15 letters found
Clue 4
Skip counting
The robot footprints go down the hallway. Skip count the metal toe prints by twos to follow the path.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
A
50
65
42
6
80
130
55
140
A
50
65
65
22
60
140
22
55
140
21
35
110
8
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, ___, 60, 70A
Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12D
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130E
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26B
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27O
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100N
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75S
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, ___, 60, 65G
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45W
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160L
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150Y
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, ___, 70, 80U
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48H
Skip-count by 2s. Fill the blank: 2, 4, ___, 8, 10I
0/14 letters found
Clue 5
Missing addends — the last clue
The power bar needs ten points to work. We only have six points. Find how many more points we need to get to ten.
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
3 + ___ = 5
10 + ___ = 13
4 + ___ = 9
1 + ___ = 7
6 + ___ = 16
1 + ___ = 10
4 + ___ = 5
7 + ___ = 19
4 + ___ = 11
5 + ___ = 16
8 + ___ = 12
Step 2 — cross out the sentence with each answer
1.The villain zooms over the high gate, then blows soapy bubbles in the air.
2.The villain slices open the locked safe, then charges up in the sunlight.
3.The villain slices open the locked safe, then sets off the shop bells.
4.The villain picks up the metal box, then beams a bright yellow light.
5.The villain picks up the metal box, then puffs out a cloud of grey soot.
6.The villain hears the secret lock code, then blows soapy bubbles in the air.
7.The villain picks up the metal box, then sets off the shop bells.
8.The villain zooms over the high gate, then beams a bright yellow light.
9.The villain slices open the locked safe, then blows soapy bubbles in the air.
10.The villain digs under the workshop floor, then puffs out a cloud of grey soot.
11.The villain slices open the locked safe, then beams a bright yellow light.
12.The villain zooms over the high gate, then charges up in the sunlight.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Spark Yard Mystery
Culprit: Gearbox (jet booster · search light · left side leak · glass bulb · rust spray)
- Clue 1 (Addition): "NO BUBBLE FAN ON THE THIEF"38 + 17 = 55 (N) · 50 + 36 = 86 (U) · 25 + 12 = 37 (H) · 33 + 36 = 69 (E) · 30 + 33 = 63 (A) · 39 + 20 = 59 (L) · 23 + 17 = 40 (I) · 21 + 9 = 30 (O) · 32 + 25 = 57 (T) · 30 + 34 = 64 (F) · 42 + 34 = 76 (B)
- Clue 2 (Place value): "AN OIL TRAIL LEADS TO THE LEFT"What number has 1 ten and 7 ones? = 17 (A) · What number has 1 ten and 3 ones? = 13 (R) · What number has 8 tens and 2 ones? = 82 (S) · What number has 3 tens and 3 ones? = 33 (D) · What number has 2 tens and 0 ones? = 20 (E) · What number has 7 tens and 7 ones? = 77 (N) · What number has 8 tens and 4 ones? = 84 (F) · What number has 3 tens and 9 ones? = 39 (H) · What number has 5 tens and 7 ones? = 57 (T) · What number has 4 tens and 6 ones? = 46 (I) · What number has 1 ten and 2 ones? = 12 (L) · What number has 2 tens and 8 ones? = 28 (O)
- Clue 3 (Subtraction): "RUST SPRAY WILL FREEZE THE SYSTEM"79 - 5 = 74 (R) · 67 - 35 = 32 (W) · 62 - 19 = 43 (A) · 46 - 22 = 24 (L) · 57 - 37 = 20 (Z) · 124 - 37 = 87 (E) · 55 - 15 = 40 (I) · 85 - 2 = 83 (U) · 48 - 2 = 46 (P) · 102 - 16 = 86 (M) · 24 - 13 = 11 (Y) · 53 - 30 = 23 (H) · 58 - 33 = 25 (S) · 63 - 5 = 58 (F) · 78 - 10 = 68 (T)
- Clue 4 (Skip counting): "A SHINY GLASS BULB GLOWED"Skip-count by 10s. Fill the blank: 10, 20, 30, 40, ___, 60, 70 = 50 (A) · Skip-count by 2s. Fill the blank: 2, 4, 6, ___, 10, 12 = 8 (D) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130 = 110 (E) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, ___, 24, 26 = 22 (B) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27 = 21 (O) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100 = 80 (N) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75 = 65 (S) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, ___, 60, 65 = 55 (G) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45 = 35 (W) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160 = 140 (L) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150 = 130 (Y) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, ___, 70, 80 = 60 (U) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48 = 42 (H) · Skip-count by 2s. Fill the blank: 2, 4, ___, 8, 10 = 6 (I)
- Clue 5 (Missing addends): surviving statement (box 8) → Gearbox3 + ___ = 5 = 2 · 10 + ___ = 13 = 3 · 4 + ___ = 9 = 5 · 1 + ___ = 7 = 6 · 6 + ___ = 16 = 10 · 1 + ___ = 10 = 9 · 4 + ___ = 5 = 1 · 7 + ___ = 19 = 12 · 4 + ___ = 11 = 7 · 5 + ___ = 16 = 11 · 8 + ___ = 12 = 4
About this mystery
- Grade level
- Grade 2 math
- Math topics
- Addition, Place value, Subtraction, Skip counting, Missing addends
- Reading level
- grades 1-2
- Theme
- The Spark Yard Mystery — set in Robo-City Spark Yard
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects