Grade 1Reading: grades 1-2Place valueAdditionSubtractionSkip countingMissing addends
The Case of the Missing Golden Compass
Oh no! Someone took the golden compass from the treehouse. We need to find the sneaky rival agent who took it! Look for clues in the yard.
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 | Spy Gear | Special Skill | Writing Hand | Hair Color | Agent Weakness |
|---|---|---|---|---|---|
| Agent Kim | Night Goggles | Fast Run | Right Handed | Yellow Hair | Scared of Bugs |
| Agent Ben | Spy Camera | Water Splash | Right Handed | Red Hair | Scared of Bugs |
| Agent Dan | Night Goggles | Super Jump | Right Handed | Brown Hair | Loves Cookie Crumbs |
| Agent Hal | Night Goggles | Quiet Climb | Right Handed | Red Hair | Loves Cookie Crumbs |
| Agent Rex | Invisible Ink | Water Splash | Right Handed | Red Hair | Loves Cookie Crumbs |
| Agent Bob | Laser Pointer | Fast Run | Left Handed | Red Hair | Loves Cookie Crumbs |
| Agent Fay | Night Goggles | Fast Run | Right Handed | Brown Hair | Loves Cookie Crumbs |
| Agent Ted | Spy Camera | Water Splash | Right Handed | Red Hair | Loves Cookie Crumbs |
| Agent Max | Walkie Talkie | Fast Run | Left Handed | Brown Hair | Dislikes Loud Noises |
| Agent Amy | Invisible Ink | Water Splash | Left Handed | Brown Hair | Dislikes Loud Noises |
| Agent Liz | Laser Pointer | Water Splash | Left Handed | Brown Hair | Dislikes Loud Noises |
| Agent Pip | Spy Camera | Super Jump | Left Handed | Yellow Hair | Loves Cookie Crumbs |
| Agent Jan | Laser Pointer | Fast Run | Left Handed | Yellow Hair | Loves Cookie Crumbs |
| Agent Roy | Night Goggles | Super Jump | Left Handed | Red Hair | Dislikes Loud Noises |
| Agent Leo | Laser Pointer | Super Jump | Left Handed | Red Hair | Dislikes Loud Noises |
| Agent Joy | Walkie Talkie | Super Jump | Right Handed | Red Hair | Loves Cookie Crumbs |
| Agent Zoe | Night Goggles | Sneak Walk | Right Handed | Brown Hair | Loves Cookie Crumbs |
| Agent Mia | Invisible Ink | Sneak Walk | Left Handed | Yellow Hair | Scared of Bugs |
| Agent Ned | Laser Pointer | Quiet Climb | Left Handed | Brown Hair | Scared of Bugs |
| Agent Sue | Night Goggles | Water Splash | Right Handed | Red Hair | Loves Cookie Crumbs |
| Agent Gus | Laser Pointer | Fast Run | Right Handed | Brown Hair | Dislikes Loud Noises |
Clue 1
Place value
We found a locked spy box. The code uses tens and ones to show a secret number.
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
13
67
90
81
56
90
16
T
13
50
43
50
16
62
T
13
28
36
90
65
28
43
90
T
13
61
92
43
22
64
What number has 1 ten and 3 ones?T
What number has 6 tens and 1 one?C
What number has 2 tens and 8 ones?U
What number has 9 tens and 0 ones?E
What number has 4 tens and 3 ones?I
What number has 6 tens and 4 ones?B
What number has 1 ten and 6 ones?N
What number has 5 tens and 0 ones?D
What number has 2 tens and 2 ones?M
What number has 5 tens and 6 ones?G
What number has 3 tens and 6 ones?S
What number has 8 tens and 1 one?A
What number has 6 tens and 5 ones?Q
What number has 6 tens and 7 ones?H
What number has 6 tens and 2 ones?O
What number has 9 tens and 2 ones?L
0/16 letters found
Clue 2
Addition
Let us count the spy gear. We need to add the gadgets in both green bags.
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
2
13
9
11
20
14
3
T
2
9
T
2
13
9
19
3
T
2
9
20
8
T
2
13
T
2
13
9
14
8
18
13
T
2
13
6
19
4
1 + 1 =T
6 + 8 =R
2 + 6 =I
6 + 7 =H
1 + 2 =O
12 + 6 =G
7 + 4 =Y
1 + 5 =A
7 + 12 =N
7 + 2 =E
14 + 6 =W
1 + 3 =D
0/12 letters found
Clue 3
Subtraction
The sprinkler washed some clues away. Let us subtract to see how many are left.
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
5
11
19
2
3
19
4
6
12
4
7
19
3
T
5
2
T
5
18
9
9
19
15
T
5
18
19
4
T
5
1
18
18
6
10
19
2
14 - 9 =T
19 - 1 =O
19 - 7 =Y
13 - 2 =H
9 - 6 =N
6 - 4 =S
20 - 1 =E
13 - 4 =P
19 - 4 =D
6 - 5 =C
10 - 4 =K
7 - 3 =A
12 - 2 =I
8 - 1 =G
0/14 letters found
Clue 4
Skip counting
Follow the footsteps on the path. They skip by twos all the way to the gate.
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
100
130
30
9
42
27
120
45
140
21
16
45
27
120
9
30
16
130
120
35
45
110
16
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120W
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45H
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160S
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20R
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27T
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55A
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33N
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, ___, 35, 40F
Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15O
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150E
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48U
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, ___, 130, 140D
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130I
0/13 letters found
Clue 5
Missing addends — the last clue
We need eight badges for our map. We only have five. How many more do we need
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
4 + ___ = 10
5 + ___ = 7
3 + ___ = 4
4 + ___ = 7
3 + ___ = 8
9 + ___ = 13
10 + ___ = 22
4 + ___ = 12
5 + ___ = 14
6 + ___ = 13
6 + ___ = 16
Step 2 — cross out the sentence with each answer
1.The villain snapped a photo with a spy camera, then made a big water splash in the pool.
2.The villain whispered into a walkie talkie, then did a super jump over the hedge.
3.The villain shined a bright laser pointer, then made a fast run across the lawn.
4.The villain whispered into a walkie talkie, then did a sneak walk past the dog.
5.The villain wrote a note in invisible ink, then made a quiet climb up the ladder.
6.The villain wrote a note in invisible ink, then made a big water splash in the pool.
7.The villain turned on the night goggles, then made a fast run across the lawn.
8.The villain shined a bright laser pointer, then did a sneak walk past the dog.
9.The villain whispered into a walkie talkie, then made a fast run across the lawn.
10.The villain turned on the night goggles, then made a quiet climb up the ladder.
11.The villain turned on the night goggles, then made a big water splash in the pool.
12.The villain turned on the night goggles, then did a super jump over the hedge.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Missing Golden Compass
Culprit: Agent Sue (Night Goggles · Water Splash · Right Handed · Red Hair · Loves Cookie Crumbs)
- Clue 1 (Place value): "THE AGENT DID NOT USE QUIET CLIMB"What number has 1 ten and 3 ones? = 13 (T) · What number has 6 tens and 1 one? = 61 (C) · What number has 2 tens and 8 ones? = 28 (U) · What number has 9 tens and 0 ones? = 90 (E) · What number has 4 tens and 3 ones? = 43 (I) · What number has 6 tens and 4 ones? = 64 (B) · What number has 1 ten and 6 ones? = 16 (N) · What number has 5 tens and 0 ones? = 50 (D) · What number has 2 tens and 2 ones? = 22 (M) · What number has 5 tens and 6 ones? = 56 (G) · What number has 3 tens and 6 ones? = 36 (S) · What number has 8 tens and 1 one? = 81 (A) · What number has 6 tens and 5 ones? = 65 (Q) · What number has 6 tens and 7 ones? = 67 (H) · What number has 6 tens and 2 ones? = 62 (O) · What number has 9 tens and 2 ones? = 92 (L)
- Clue 2 (Addition): "THEY WROTE THE NOTE WITH THE RIGHT HAND"1 + 1 = 2 (T) · 6 + 8 = 14 (R) · 2 + 6 = 8 (I) · 6 + 7 = 13 (H) · 1 + 2 = 3 (O) · 12 + 6 = 18 (G) · 7 + 4 = 11 (Y) · 1 + 5 = 6 (A) · 7 + 12 = 19 (N) · 7 + 2 = 9 (E) · 14 + 6 = 20 (W) · 1 + 3 = 4 (D)
- Clue 3 (Subtraction): "THE SNEAKY AGENT STOPPED TO EAT COOKIES"14 - 9 = 5 (T) · 19 - 1 = 18 (O) · 19 - 7 = 12 (Y) · 13 - 2 = 11 (H) · 9 - 6 = 3 (N) · 6 - 4 = 2 (S) · 20 - 1 = 19 (E) · 13 - 4 = 9 (P) · 19 - 4 = 15 (D) · 6 - 5 = 1 (C) · 10 - 4 = 6 (K) · 7 - 3 = 4 (A) · 12 - 2 = 10 (I) · 8 - 1 = 7 (G)
- Clue 4 (Skip counting): "WE FOUND A STRAND OF RED HAIR"Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, ___, 110, 120 = 100 (W) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, ___, 40, 45 = 35 (H) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160 = 140 (S) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, 14, ___, 18, 20 = 16 (R) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27 = 21 (T) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, ___, 50, 55 = 45 (A) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33 = 27 (N) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, ___, 35, 40 = 30 (F) · Skip-count by 3s. Fill the blank: 3, 6, ___, 12, 15 = 9 (O) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, ___, 140, 150 = 130 (E) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, ___, 45, 48 = 42 (U) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, ___, 130, 140 = 120 (D) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ___, 120, 130 = 110 (I)
- Clue 5 (Missing addends): surviving statement (box 11) → Agent Sue4 + ___ = 10 = 6 · 5 + ___ = 7 = 2 · 3 + ___ = 4 = 1 · 4 + ___ = 7 = 3 · 3 + ___ = 8 = 5 · 9 + ___ = 13 = 4 · 10 + ___ = 22 = 12 · 4 + ___ = 12 = 8 · 5 + ___ = 14 = 9 · 6 + ___ = 13 = 7 · 6 + ___ = 16 = 10
About this mystery
- Grade level
- Grade 1 math
- Math topics
- Place value, Addition, Subtraction, Skip counting, Missing addends
- Reading level
- grades 1-2
- Theme
- The Case of the Missing Golden Compass — set in The Backyard Treehouse HQ
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects