Lesson Plan
Add or Multiply?
Students will be able to differentiate between addition and multiplication word problems by identifying specific keywords and understanding their context.
Understanding when to add versus when to multiply is a fundamental skill in solving word problems. This lesson helps students build a solid foundation for more complex mathematical reasoning.
Audience
4th Grade Students
Time
30 minutes
Approach
Interactive slides, guided examples, and independent practice.
Materials
Smartboard or Projector, Add or Multiply? Slide Deck, and Keyword Problem Solver Worksheet
Prep
Review Materials
10 minutes
- Review the Add or Multiply? Slide Deck to familiarize yourself with the content and talking points.
- Print copies of the Keyword Problem Solver Worksheet for each student.
- Ensure projector/smartboard is set up and ready.
Step 1
Introduction & Warm-Up
5 minutes
Begin by asking students what they remember about addition and multiplication. Present the problem: 'I have 3 apples, and my friend gives me 2 more. How many do I have in total?' and 'I have 3 bags, and each bag has 2 apples. How many do I have in total?' Discuss how 'total' can mean different things depending on the problem.
Step 2
Keyword Detective (Slides & Discussion)
10 minutes
Project the Add or Multiply? Slide Deck. Go through slides 1-4, introducing keywords for addition and multiplication. Emphasize that some words, like 'total,' need context. Focus on 'each' as a key indicator for multiplication when paired with 'total.' Engage students with questions about why certain words suggest addition or multiplication.
Step 3
Example Problems: Solve Together
10 minutes
Continue with the Add or Multiply? Slide Deck, going through example problems on slides 5-12. For each problem, guide students to:
1. Identify keywords.
2. Determine if it's an addition or multiplication problem.
3. Write the equation.
4. Briefly discuss how a picture could represent the problem.
Step 4
Independent Practice: Worksheet
5 minutes
Distribute the Keyword Problem Solver Worksheet. Have students complete the first few problems independently, applying what they've learned. Circulate to provide support. If time allows, review one or two problems as a class.
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Slide Deck
Add or Multiply? Become a Word Problem Detective!
Let's uncover the secrets to solving word problems!
Welcome students and introduce the topic: solving word problems! Ask them if they've ever found word problems tricky. Explain that today we'll learn some detective skills for figuring out if we need to add or multiply.
The Tricky Word: "Total"
Sometimes finding the 'total' means adding.
Sometimes finding the 'total' means multiplying.
How do we know the difference?
Start with a thought-provoking question. Ask students for examples of when they've heard the word 'total'. Guide them to see it can be used for both summing separate groups and for finding the whole of equal groups. This sets up the need for more specific keywords.
Addition Keywords
- Add
- Sum
- In all
- Altogether
- Total (when combining different groups or amounts)
- Plus
- Increase
Introduce common addition keywords. Give a quick, simple example for each keyword to make it concrete. Encourage students to think of other words that mean 'put together' or 'find the sum.'
Multiplication Keywords
- Multiply
- Product
- Times
- Each (when referring to equal groups)
- Per
- Of (especially with fractions or percentages, but can be a keyword for whole numbers too like 'groups of')
- Total (when combining equal groups or amounts using 'each' or 'per')
Introduce common multiplication keywords. Explicitly highlight 'each' and 'per' as strong indicators, especially when asking for a 'total' of equal groups. Give examples like '3 apples in each bag'.
Example Problem 1
Sarah had 6 stickers. Her friend gave her 3 more. How many stickers does Sarah have in all?
Problem 1: Guide students to identify 'how many more' as an addition keyword. Write the equation and briefly discuss a visual representation (e.g., drawing two groups and counting on).
Example Problem 2
There are 6 baskets, and each basket has 3 apples. What is the total number of apples?
Problem 2: Guide students to identify 'each' and 'total' together for multiplication. Emphasize that 'each' is key here. Discuss drawing 4 groups of 2.
Example Problem 3
Tom has 3 blue marbles and 6 red marbles. How many marbles does he have altogether?
Problem 3: Look for 'altogether'. This is a clear addition problem. Visual: drawing separate items and counting them together.
Example Problem 4
A baker made 3 trays of cookies. There are 6 cookies on each tray. How many cookies did the baker make in total?
Problem 4: Identify 'groups of' or implied equal groups, and 'how many' for multiplication. Visual: Drawing arrays or equal groups.
Example Problem 5
A cat slept for 3 hours in the morning and 6 hours in the afternoon. How many hours did the cat sleep combined?
Problem 5: 'Combined' is a strong addition keyword. Visual: Combining two sets of objects.
Example Problem 6
There are 6 rows of chairs in the classroom. Each row has 3 chairs. How many chairs are there in all?
Problem 6: Another 'each' scenario, clearly indicating multiplication. Visual: 6 rows of 3 chairs.
Example Problem 7
My plant grew 3 inches last week and increased by another 6 inches this week. What is its total growth?
Problem 7: 'Increase by' is an addition cue. Visual: Starting with an amount and adding more.
Example Problem 8
John has 3 toy cars. His brother has twice as many. How many toy cars does his brother have?
Problem 8: This problem uses 'twice as many' which implies multiplication by 2. This is a good challenge problem for 4th graders to think beyond direct keywords. Visual: Draw one set, then draw it again.
You're a Keyword Master!
Remember to look for clues:
- Are you putting different things together? Think ADDITION.
- Are you putting equal groups together? Think MULTIPLICATION.
You got this, Word Problem Detectives!
Conclude by reminding students to always look for keywords and think about whether the problem is combining different groups (addition) or equal groups (multiplication). Encourage them to draw pictures if they are unsure.
Worksheet
Keyword Problem Solver: Add or Multiply?
Directions: Read each word problem carefully. Identify the keywords that tell you whether to add or multiply. Write down the equation and draw a picture or model to represent the problem.
---
## Problem 1
Maria has 6 red balloons and 3 blue balloons. How many balloons does she have altogether?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 2
There are 6 boxes, and each box contains 3 pencils. What is the total number of pencils?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 3
A farmer planted 3 apple trees and 6 pear trees. How many trees did he plant in total?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 4
Sam bought 6 packs of stickers. Each pack has 3 stickers. How many stickers did Sam buy in all?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 5
My dog ate 3 treats in the morning and 6 treats in the evening. How many treats did he eat combined?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 6
There are 6 students, and each student needs 3 erasers. How many erasers are needed altogether?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 7
A library has 3 fiction books and 6 non-fiction books. What is the sum of the books?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 8
A recipe calls for 3 cups of flour. If you want to make the recipe 6 times, how many cups of flour do you need?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 9
There were 6 birds on one branch and 3 birds on another branch. How many birds were there in total on both branches?
Keywords Identified:
Equation:
Draw a Picture/Model:
---
## Problem 10
A teacher has 6 groups of students, with 3 students per group. What is the product of students?
Worksheet
Multiply by 3s and 6s: Practice Time!
Directions: Solve each multiplication problem. Show your work or draw a picture if it helps you!
---
## Part 1: Multiply by 3
1. 3 x 2 =
2. 3 x 5 =
3. 3 x 8 =
4. 3 x 0 =
5. 3 x 7 =
6. 3 x 4 =
7. 3 x 9 =
8. 3 x 1 =
9. 3 x 10 =
10. 3 x 6 =
---
## Part 2: Multiply by 6
1. 6 x 2 =
2. 6 x 5 =
3. 6 x 8 =
4. 6 x 0 =
5. 6 x 7 =
6. 6 x 4 =
7. 6 x 9 =
8. 6 x 1 =
9. 6 x 10 =
10. 6 x 3 =
---
## Part 3: Mixed Practice
1. 3 x 6 =
2. 6 x 5 =
3. 3 x 9 =
4. 6 x 8 =
5. 3 x 7 =
6. 6 x 4 =
7. 3 x 3 =
8. 6 x 6 =
9. 3 x 12 =
10. 6 x 11 =