Lesson Plan
What's The Missing Piece?
Students will be able to find the missing numbers in addition and subtraction equations within 10.
Understanding how to find missing numbers strengthens number sense and prepares students for more complex algebraic thinking in the future. It's like being a math detective!
Audience
1st Grade
Time
30 minutes
Approach
Through interactive slides, partner discussions, and independent practice, students will uncover the missing numbers in equations.
Materials
Whiteboard or Projector, Slide Deck: What's The Missing Piece?, Markers or Chalk, Worksheet: Find The Missing Piece (one per student), and Pencils
Prep
Teacher Preparation
10 minutes
- Review the Slide Deck: What's The Missing Piece? and practice the Script: What's The Missing Piece? to familiarize yourself with the content and flow.
- Print one copy of the Worksheet: Find The Missing Piece per student.
- Ensure the projector or whiteboard is ready for displaying the slide deck.
- Have markers or chalk readily available.
Step 1
Warm-Up: Number Puzzles (5 minutes)
5 minutes
- Display the first slide of the Slide Deck: What's The Missing Piece?.
- Ask students to share what they notice about the equations. Guide them to recognize that a number is missing.
- Facilitate a brief class discussion on how they might figure out the missing number. (e.g., "If I have 3 and I want 5, how many more do I need?").
- Use the Script: What's The Missing Piece? for guiding questions and prompts.
Step 2
Introduction to Missing Numbers (10 minutes)
10 minutes
- Move through the next few slides in the Slide Deck: What's The Missing Piece? that introduce the concept of missing addends and subtrahends within 10.
- Use visual aids and manipulatives (if available, or imagine them) to demonstrate how to solve for the missing number.
- Model solving a few problems step-by-step, thinking aloud about the strategies used (e.g., counting on, counting back, using a number line).
- Encourage students to participate by calling out answers or suggesting strategies. Refer to the Script: What's The Missing Piece? for specific phrasing.
Step 3
Partner Practice: Solve It Together (8 minutes)
8 minutes
- Display a slide with a few missing number problems for partner work.
- Pair students up and have them discuss and solve the problems together.
- Circulate around the room, providing support and listening to their strategies. Encourage them to explain their thinking to each other.
- Bring the class back together and have a few pairs share their solutions and strategies for one or two problems.
Step 4
Independent Practice: Find The Missing Piece (5 minutes)
5 minutes
- Distribute the Worksheet: Find The Missing Piece to each student.
- Instruct students to independently solve the missing number problems on the worksheet.
- Remind them to use the strategies discussed during the lesson.
- Collect the worksheets at the end for assessment or review.
Step 5
Cool Down: Quick Check (2 minutes)
2 minutes
- Display the final slide with one simple missing number problem.
- Ask students to quickly write their answer on a scratch piece of paper or show with their fingers.
- This serves as a quick check for understanding before the end of the lesson. Refer to the Script: What's The Missing Piece? for the cool-down prompt.
Slide Deck
What's The Missing Piece?
Are you ready to be a Math Detective?
Welcome students and introduce the exciting theme of being a 'math detective'. Briefly explain that today they will solve number mysteries. Display the title slide.
Mystery Numbers!
Look at these equations. What do you notice?
3 + __ = 5
10 - __ = 7
Warm-up activity. Ask students to observe the equations and talk about what they notice. Guide them to realize a number is hidden. No need to solve yet, just notice the mystery.
Our Mission Today
Today, we will learn how to find the missing numbers in addition and subtraction problems!
It's like solving a puzzle!
Introduce the objective of the lesson clearly. Explain that they will learn how to find those missing numbers.
Finding the Missing PLUS!
When we have an addition problem with a missing number, like this:
4 + __ = 7
How many more do we need to get to 7?
Explain 'missing addend' using an example. Use visual cues or ask students to imagine objects. Model counting on.
Let's Solve It!
4 + 3 = 7
We can count on from 4: 5, 6, 7. That's 3 more!
Show the solution for the missing addend problem. Reinforce the concept of counting on or using known facts.
Finding the Missing MINUS!
What about subtraction problems, like this?
9 - __ = 5
If we start with 9, and we want to end up with 5, how many did we take away?
Explain 'missing subtrahend' using an example. Use visual cues or ask students to imagine objects. Model counting back or using a part-part-whole relationship.
Let's Solve It!
9 - 4 = 5
We can count back from 9: 8, 7, 6, 5. That's 4 we took away!
Show the solution for the missing subtrahend problem. Reinforce the concept of counting back or thinking of related addition.
Partner Up! Math Detectives!
Work with a partner to find the missing numbers!
- 6 + __ = 8
- 7 - __ = 2
- __ + 3 = 10
Provide problems for partner practice. Encourage students to talk to each other about their strategies.
Last Mystery of the Day!
What's the missing number?
2 + __ = 9
Quick cool-down assessment. Ask students to show their answer (e.g., on fingers, mini-whiteboard, or just call out).
Great Job, Math Detectives!
You found all the missing pieces!
Keep practicing your number puzzles!
Concluding slide. Reinforce their success as math detectives.
Script
What's The Missing Piece? - Teacher Script
Warm-Up: Number Puzzles (5 minutes)
(Display Slide 2: Mystery Numbers!)
"Good morning, future Math Detectives! Today, we have a very important mission: to solve some number mysteries! Look at the equations on the screen. What do you notice about them? Turn and talk to a partner for 30 seconds. What do you see that's a little different?"
"Can anyone share what they noticed? Yes, [Student Name]?" (Guide them to say there's an empty box or a missing number.)
"Exactly! There's a missing number, a hidden piece of the puzzle! How do you think we could figure out what that missing number is? Don't tell me the answer yet, just how you might figure it out."
"Great ideas! We're going to explore how to find those missing pieces today."
Introduction to Missing Numbers (10 minutes)
(Display Slide 3: Our Mission Today)
"Our mission today is to become expert Math Detectives and find the missing numbers in addition and subtraction problems. It's like being a super-sleuth for numbers!"
(Display Slide 4: Finding the Missing PLUS!)
"Let's start with addition. Look at this problem: 4 + __ = 7. We know we start with 4. We want to get to 7. How many more do we need to add to 4 to reach 7? Think about counting on. We have 4... then what? Keep counting until you get to 7, and keep track of how many fingers you put up!"
"Let's try it together. Start with 4. Count with me: 5 (one finger), 6 (two fingers), 7 (three fingers)! How many more did we add?"
(Display Slide 5: Let's Solve It!)
"That's right, 3 more! So, 4 + 3 = 7. We found the missing piece!"
(Display Slide 6: Finding the Missing MINUS!)
"Now, let's look at subtraction. Here's a new mystery: 9 - __ = 5. This time, we start with 9. We take away some number, and we are left with 5. How many did we take away? Think about counting back from 9 until we get to 5. How many steps did you take?"
"Let's try counting back together. Start at 9. Count back until you reach 5: 8 (one step), 7 (two steps), 6 (three steps), 5 (four steps)! How many did we take away?"
(Display Slide 7: Let's Solve It!)
"Excellent! We took away 4. So, 9 - 4 = 5. Another mystery solved!"
"Remember, for missing addends, you can count on. For missing subtrahends, you can count back, or you can think, 'What do I add to the smaller number to get the bigger number?'"
Partner Practice: Solve It Together (8 minutes)
(Display Slide 8: Partner Up! Math Detectives!)
"Alright, Math Detectives, it's time to team up! I want you to work with your elbow partner to solve the three missing number problems on the screen. Talk about your strategies and help each other out. You have 8 minutes. Go!"
(Circulate, listen to discussions, offer support, and prompt thinking: "How did you figure that out? What strategy did you use? Could you show your partner?")
"Okay, class, let's come back together. Who would like to share how they solved the first problem, 6 + __ = 8? [Student Name], what did you and your partner find?"
"How about the second one, 7 - __ = 2? [Student Name]?"
"And the last one, __ + 3 = 10? This one started with the missing number! How did you solve it? [Student Name]?"
"Fantastic teamwork, everyone! You're really getting the hang of this."
Independent Practice: Find The Missing Piece (5 minutes)
"Now it's time for some independent detective work! I'm going to hand out a Worksheet: Find The Missing Piece to everyone. Your job is to solve all the missing number problems by yourself. Remember to use the strategies we just talked about: counting on, counting back, or using your addition and subtraction facts. Take your time and do your best!"
(Distribute worksheets. Collect them after 5 minutes.)
Cool Down: Quick Check (2 minutes)
(Display Slide 9: Last Mystery of the Day!)
"Alright, Math Detectives, for our very last puzzle of the day, look at this problem on the screen: 2 + __ = 9. On your scratch paper, or just by thinking, what's the missing number? Once you have it, you can show me with your fingers, or give me a thumbs up if you know!"
"Excellent! It looks like many of you found the missing piece! You are all becoming super Math Detectives!"
(Display Slide 10: Great Job, Math Detectives!)
"You did a wonderful job today finding all the missing pieces in our number puzzles. Keep practicing, and you'll be math masters in no time!"
Worksheet
Find The Missing Piece
Name: _________________________
Date: _________________________
## Be a Math Detective! Find the missing number in each equation.
Part 1: Addition Puzzles
-
3 + ____ = 6
-
____ + 5 = 7
-
2 + ____ = 8
-
____ + 4 = 9
-
7 + ____ = 10
### Part 2: Subtraction Puzzles -
8 - ____ = 4
-
10 - ____ = 3
-
6 - ____ = 1
-
9 - ____ = 5
-
7 - ____ = 0
### Part 3: Mixed Mysteries! -
4 + ____ = 10
-
5 - ____ = 2
-
____ + 1 = 9
-
8 - ____ = 8
-
1 + ____ = 7
Answer Key
Find The Missing Piece - Answer Key
Part 1: Addition Puzzles
-
3 + 3 = 6
- Thought Process: Start at 3 and count up to 6. (4, 5, 6) That's 3 counts.
-
2 + 5 = 7
- Thought Process: Start at 5 and count up to 7. (6, 7) That's 2 counts.
-
2 + 6 = 8
- Thought Process: Start at 2 and count up to 8. (3, 4, 5, 6, 7, 8) That's 6 counts.
-
5 + 4 = 9
- Thought Process: Start at 4 and count up to 9. (5, 6, 7, 8, 9) That's 5 counts.
-
7 + 3 = 10
- Thought Process: Start at 7 and count up to 10. (8, 9, 10) That's 3 counts.
## Part 2: Subtraction Puzzles
- Thought Process: Start at 7 and count up to 10. (8, 9, 10) That's 3 counts.
-
8 - 4 = 4
- Thought Process: Start at 8 and count back to 4. (7, 6, 5, 4) That's 4 counts. Or, think 4 + ? = 8.
-
10 - 7 = 3
- Thought Process: Start at 10 and count back to 3. (9, 8, 7, 6, 5, 4, 3) That's 7 counts. Or, think 3 + ? = 10.
-
6 - 5 = 1
- Thought Process: Start at 6 and count back to 1. (5, 4, 3, 2, 1) That's 5 counts. Or, think 1 + ? = 6.
-
9 - 4 = 5
- Thought Process: Start at 9 and count back to 5. (8, 7, 6, 5) That's 4 counts. Or, think 5 + ? = 9.
-
7 - 7 = 0
- Thought Process: Start at 7 and count back to 0. (6, 5, 4, 3, 2, 1, 0) That's 7 counts. Or, think 0 + ? = 7.
## Part 3: Mixed Mysteries!
- Thought Process: Start at 7 and count back to 0. (6, 5, 4, 3, 2, 1, 0) That's 7 counts. Or, think 0 + ? = 7.
-
4 + 6 = 10
- Thought Process: Start at 4 and count up to 10. (5, 6, 7, 8, 9, 10) That's 6 counts.
-
5 - 3 = 2
- Thought Process: Start at 5 and count back to 2. (4, 3, 2) That's 3 counts. Or, think 2 + ? = 5.
-
8 + 1 = 9
- Thought Process: Start at 1 and count up to 9. (2, 3, 4, 5, 6, 7, 8, 9) That's 8 counts.
-
8 - 0 = 8
- Thought Process: If you start with 8 and end with 8, you took away nothing. Or, think 8 + ? = 8.
-
1 + 6 = 7
- Thought Process: Start at 1 and count up to 7. (2, 3, 4, 5, 6, 7) That's 6 counts.