Lesson Plan
Operation Detectives Lesson Plan
Students will become "Operation Detectives" by identifying whether mixed problems require addition or subtraction (with and without regrouping) and solving them, achieving 80% accuracy on 4 of 5 trials each session.
Clear operation identification builds foundational math skills, boosts confidence for learners with autism, and supports IEP/504 goals by scaffolding mixed-skill practice in short, structured sessions.
Audience
Enhanced Autism Classroom Students
Time
10 sessions × 15 minutes each
Approach
Thematic, scaffolded practice in 10 focused 15-minute sessions.
Materials
Whiteboard and Dry-Erase Markers, Counting Counters or Place Value Blocks, Operation Detectives Worksheets, Operation Detectives Detective Notebooks, and Operation Detectives Game Cards
Prep
Preparation
30 minutes
- Review all Operation Detectives Worksheets.
- Print and collate one copy per student per session.
- Prepare Operation Detectives Game Cards by cutting and shuffling.
- Assemble student detective notebooks: cover sheet, operation key, and answer logging pages.
- Gather counters/place-value blocks and markers for group use.
Step 1
Session 1: Detective Orientation
15 minutes
- Introduce the "Operation Detective" theme and distribute detective notebooks.
- Explain addition vs subtraction definitions with examples on the whiteboard.
- Students complete 5–7 identification-only items on [Operation Detectives Worksheets] (no regrouping).
- Review answers as a group, praising correct detective work.
Step 2
Session 2: Addition Sleuthing
15 minutes
- Quick warm-up: write 3 addition equations; have students say “+ is add.”
- Model solving two multi-digit addition problems without regrouping.
- Students solve 5 addition items on [Operation Detectives Worksheets].
- Students log operations and answers in their notebooks; share one strategy.
Step 3
Session 3: Subtraction Sleuthing
15 minutes
- Warm-up: 3 subtraction facts; students say “– is subtract.”
- Demonstrate subtraction without regrouping using counters.
- Students complete 5 subtraction items on [Operation Detectives Worksheets].
- Check as a class; emphasize operation identification before computing.
Step 4
Session 4: Mixed Practice I
15 minutes
- Review addition vs subtraction cues for 2 minutes.
- Students receive 8 mixed problems (no regrouping) on [Operation Detectives Worksheets].
- In pairs, use counters/place-value blocks to solve and confirm answers.
- Class discussion: detectives share how they chose the operation.
Step 5
Session 5: Introduction to Regrouping
15 minutes
- Teach addition with regrouping using place-value blocks.
- Model one problem; highlight carrying steps in detective notebook.
- Students solve 5 addition-with-regrouping items on [Operation Detectives Worksheets].
- Debrief: students circle where regrouping occurred.
Step 6
Session 6: Regrouping in Subtraction
15 minutes
- Demonstrate subtraction with regrouping using counters.
- Students solve 5 subtraction-with-regrouping problems.
- Monitor for correct borrowing procedures; scaffold with counters.
- Students note regrouping steps in their detective notebooks.
Step 7
Session 7: Mixed Practice II
15 minutes
- Warm-up identification quiz: 6 operations on board.
- Students solve 8 mixed problems (with/without regrouping) on [Operation Detectives Worksheets].
- Partner check: students swap notebooks and confirm operations.
- Quick share: one detective explains a tricky problem.
Step 8
Session 8: Detective Game Prep
15 minutes
- Introduce [Operation Detectives Game Cards]: each card has a mixed problem.
- Model how to draw a card, identify the operation, solve, and log in notebook.
- Students practice with 3 game cards each in small groups.
- Review common errors and correct strategies.
Step 9
Session 9: Mystery Mansion Game
15 minutes
- Students play in pairs: draw 5 [Operation Detectives Game Cards], solve and earn "case files" for each correct answer.
- Teacher circulates, prompts operation identification if needed.
- Pairs swap and check each other’s solutions.
- Tally correct files; celebrate top detectives.
Step 10
Session 10: Final Investigation
15 minutes
- Students receive 10 mixed problems (with and without regrouping) on [Operation Detectives Worksheets].
- 10-minute timed challenge: identify and solve as many as possible.
- Record operations and answers in detective notebooks.
- Class review: ensure 80% accuracy; award certificates to successful detectives.
Worksheet
Operation Detectives Worksheets
Use these worksheets in conjunction with your Operation Detectives Detective Notebooks and Operation Detectives Game Cards. Each session builds on prior skills—identify the operation first, then solve!
Session 1: Detective Orientation (Identification Only)
For each problem below, write Addition or Subtraction in the blank.
- 14 + 7 Operation: _______
- 9 – 5 Operation: _______
- 23 + 8 Operation: _______
- 17 – 4 Operation: _______
- 12 + 6 Operation: _______
- 20 – 9 Operation: _______
- 6 + 15 Operation: _______
Session 2: Addition Sleuthing (No Regrouping)
Solve each addition problem below.
- 23 + 14 = _______
- 45 + 32 = _______
- 11 + 23 = _______
- 34 + 15 = _______
- 52 + 21 = _______
Session 3: Subtraction Sleuthing (No Regrouping)
Solve each subtraction problem below.
- 54 – 23 = _______
- 41 – 12 = _______
- 36 – 14 = _______
- 65 – 30 = _______
- 28 – 13 = _______
Session 4: Mixed Practice I (No Regrouping)
Identify the operation and solve.
- 22 + 11 = _______
- 50 – 25 = _______
- 13 + 24 = _______
- 47 – 22 = _______
- 31 + 15 = _______
- 40 – 18 = _______
- 19 + 14 = _______
- 56 – 33 = _______
Session 5: Addition with Regrouping
Show your carrying steps in your detective notebook and write the final answer below.
- 27 + 18 = _______
- 39 + 46 = _______
- 58 + 17 = _______
- 47 + 29 = _______
- 65 + 28 = _______
Session 6: Subtraction with Regrouping
Show your borrowing steps in your detective notebook and write the final answer below.
- 34 – 19 = _______
- 52 – 27 = _______
- 61 – 38 = _______
- 70 – 45 = _______
- 83 – 57 = _______
Session 7: Mixed Practice II (With & Without Regrouping)
Identify, solve, and show your work in your detective notebook.
- 24 + 13 = _______
- 68 – 24 = _______
- 37 + 29 = _______
- 54 – 19 = _______
- 45 + 16 = _______
- 72 – 38 = _______
- 59 + 27 = _______
- 83 – 47 = _______
Session 8: Detective Game Prep
Practice a few problems before playing with Operation Detectives Game Cards.
- 31 + 19 = _______
- 64 – 25 = _______
- 28 + 47 = _______
- 75 – 38 = _______
- 49 + 18 = _______
Session 9: Mystery Mansion Game Log
Record the five cards you draw, identify the operation, and solve each case file below.
Case 1. Problem: _______ Operation: _______ Answer: _______
Case 2. Problem: _______ Operation: _______ Answer: _______
Case 3. Problem: _______ Operation: _______ Answer: _______
Case 4. Problem: _______ Operation: _______ Answer: _______
Case 5. Problem: _______ Operation: _______ Answer: _______
Session 10: Final Investigation (Timed Challenge)
You have 10 minutes to identify and solve as many of the 10 problems below as you can. Record operation and answer.
- 28 + 37 = _______
- 65 – 29 = _______
- 47 + 58 = _______
- 83 – 46 = _______
- 36 + 27 = _______
- 74 – 38 = _______
- 59 + 26 = _______
- 92 – 57 = _______
- 68 + 29 = _______
- 81 – 34 = _______
Activity
Operation Detectives Detective Notebooks
Use this detective notebook to record your operation identification, show your work, and reflect on your strategy. Keep it with you every session to track your progress as an Operation Detective!
Operation Key
| Operation | Symbol | Clue Words |
|---|---|---|
| Addition | + | add, total, combine |
| Subtraction | – | take away, difference |
Detective Tip: Circle the symbol and underline a clue word in the problem before you begin your work.
How to Use Your Detective Notebook
- Write the Case (problem) exactly as shown.
- Circle the symbol (+ or –) and write Addition or Subtraction.
- Show your work steps in the space provided (draw counters, regroup, borrow, etc.).
- Write the Answer clearly.
- Add a short Detective Note: What clue helped you pick the operation?
Session ___ Investigation Log
Date: _______________
Case 1
Problem: _________________________
Operation: ( ) Addition ( ) Subtraction
Work Steps:
Answer: __________________________
Detective Note: _______________________________________________________________________
Case 2
Problem: _________________________
Operation: ( ) Addition ( ) Subtraction
Work Steps:
Answer: __________________________
Detective Note: _______________________________________________________________________
Case 3
Problem: _________________________
Operation: ( ) Addition ( ) Subtraction
Work Steps:
Answer: __________________________
Detective Note: _______________________________________________________________________
Case 4
Problem: _________________________
Operation: ( ) Addition ( ) Subtraction
Work Steps:
Answer: __________________________
Detective Note: _______________________________________________________________________
(Copy this page or continue numbering for more cases as needed.)
Keep your notebook neat—your detective skills shine through clear work and thoughtful notes! When you use this in class, your teacher may prompt you to share a Detective Note with the group or review specific work steps.
Game
Mystery Mansion Game Cards
Cut along the lines below to create individual cards. Shuffle and draw during the Mystery Mansion Game. Identify the operation, solve the problem, and log your answer in your detective notebook.
Card 1: 24 + 13
Card 2: 57 – 34
Card 3: 38 + 15
Card 4: 46 – 23
Card 5: 14 + 29
Card 6: 63 – 27
Card 7: 56 + 18
Card 8: 82 – 46
Card 9: 27 + 18
Card 10: 39 + 46
Card 11: 58 + 17
Card 12: 47 + 29
Card 13: 65 + 28
Card 14: 34 – 19
Card 15: 52 – 27
Card 16: 61 – 38
Card 17: 70 – 45
Card 18: 83 – 57
Card 19: 68 – 24
Card 20: 31 + 19
Use these cards in Session 9 (Mystery Mansion Game) or as extra practice in small groups. Each card challenges detectives to pick addition or subtraction (with/without regrouping) and record their solution in their Operation Detectives Detective Notebooks!