Lesson Plan
3-Digit Word Problems: Solve It!
Students will be able to accurately solve one-step addition and subtraction word problems involving three-digit numbers.
Mastering these skills helps students build a strong foundation in number sense and problem-solving, which are crucial for more complex math and real-world situations.
Audience
3rd Grade Small Group
Time
30 minutes
Approach
Through direct instruction, guided practice, and independent application.
Materials
Whiteboard or projector, 3-Digit Word Problems Slide Deck, Markers or pens, Word Problem Worksheet, and Answer Key (for teacher use)
Prep
Teacher Preparation
10 minutes
- Review the 3-Digit Word Problems Slide Deck and ensure all slides are in order.
- Print enough copies of the Word Problem Worksheet for each student.
- Have the Answer Key readily available for quick reference.
- Ensure markers/pens and a whiteboard/projector are accessible.
- Familiarize yourself with the Teacher Script to guide the lesson effectively.
- Review the generated materials as needed.
Step 1
Warm-Up: Number Talk (5 minutes)
5 minutes
- Begin with a quick number talk using 3-digit numbers. Ask students to share strategies for adding or subtracting two 3-digit numbers mentally.
- Example: "What is 250 + 130? How did you solve it?" or "What is 480 - 150?"
Step 2
Introduction: What's the Story? (5 minutes)
5 minutes
- Display the first slide of the 3-Digit Word Problems Slide Deck with the lesson title.
- Introduce the concept of word problems as "math stories" that require us to figure out what's happening and how to solve it.
- Briefly review place value for 3-digit numbers using Slide 2: "Place Value Power!"
Step 3
Direct Instruction: Our Secret Weapon (5 minutes)
5 minutes
- Introduce the CUBES strategy using Slide 3: "Our Secret Weapon: CUBES!".
- Explain each letter: Circle numbers, Underline the question, Box keywords, Evaluate (choose operation), Solve and check.
- Emphasize that CUBES helps break down word problems into manageable steps.
Step 4
Guided Practice: Solving Mysteries (8 minutes)
8 minutes
- Work through two example problems together as a group using the CUBES strategy, referring to the 3-Digit Word Problems Slide Deck (Slides 4 and 5).
- For the addition problem (Slide 4), guide students to identify the numbers, question, keywords (e.g., "altogether"), and the correct operation.
- For the subtraction problem (Slide 5), repeat the process, focusing on subtraction keywords (e.g., "left").
- Encourage students to explain their thinking at each step.
Step 5
Independent Practice: Detective Time! (5 minutes)
5 minutes
- Distribute the Word Problem Worksheet.
- Instruct students to work independently on the problems, applying the CUBES strategy.
- Circulate around the group, offering support and clarifying any questions.
- Remind them to show their work.
Step 6
Conclusion: Case Closed! (2 minutes)
2 minutes
- Bring the group back together.
- Use Slide 6: "Case Closed! What Did We Learn?" to review the main concepts.
- Ask students to share one thing they learned or found helpful today.
- Briefly collect the Word Problem Worksheet for review.
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Slide Deck
3-Digit Word Problems: Solve It!
Today, we're becoming Math Detectives to solve mysterious 3-digit number stories!
Welcome students and introduce the topic. Emphasize that word problems are like math stories.
Quick Review: Place Value Power!
Remember our hundreds, tens, and ones?
* Hundreds are big groups of 100.
* Tens are groups of 10.
* Ones are single units.
Why is knowing place value important for big numbers?
Review place value quickly, as it's crucial for 3-digit operations. Ask students for examples.
Our Secret Weapon: CUBES!
To crack word problems, we use CUBES!
* Circle the numbers.
* Underline the question.
* Box the keywords (like 'total', 'difference', 'altogether', 'left').
* Evaluate and strategize (add or subtract?).
* Solve and check!
Introduce the 'CUBES' strategy. Explain each step clearly and why it's helpful.
Let's Solve One Together! (Addition)
Sarah collected 145 stickers, and her friend Tom collected 238 stickers. How many stickers do they have altogether?
* Circle the numbers: 145, 238
* Underline the question: How many stickers do they have altogether?
* Box the keywords: altogether
* Evaluate: Addition
* Solve: 145 + 238 = ?
Guided practice example 1: Addition. Read the problem aloud, then go through CUBES step by step with student input.
Another Mystery! (Subtraction)
A baker made 367 cookies. He sold 125 cookies. How many cookies does he have left?
* Circle the numbers: 367, 125
* Underline the question: How many cookies does he have left?
* Box the keywords: left
* Evaluate: Subtraction
* Solve: 367 - 125 = ?
Guided practice example 2: Subtraction. Repeat the CUBES process.
Time to Be a Math Detective!
Now it's your turn to put on your detective hats!
Work on your Word Problem Worksheet using the CUBES strategy.
Remember to show your work!
Transition to independent practice. Explain the worksheet and circulate to provide support.
Case Closed! What Did We Learn?
Great job, Math Detectives!
* What was our secret weapon today?
* Why is the CUBES strategy helpful?
* What's one thing you learned about solving word problems with 3-digit numbers?
Conclude the lesson by reviewing CUBES and having students share their learning. Reinforce the importance of problem-solving.
Script
Teacher Script: 3-Digit Word Problems: Solve It!
## Warm-Up: Number Talk (5 minutes)
Teacher: "Good morning, Math Detectives! Let's get our brains warmed up with a quick number talk. Who can tell me a strategy for adding 250 and 130? How about subtracting 480 minus 150? Share your ideas!"
## Introduction: What's the Story? (5 minutes)
Teacher: (Display 3-Digit Word Problems Slide Deck - Slide 1) "Today, we're going on a math adventure to solve some exciting 3-digit word problems! Think of word problems like little stories that have a math puzzle hidden inside. Our job is to be super detectives and figure out the puzzle!"
(Display 3-Digit Word Problems Slide Deck - Slide 2) "Before we dive into our stories, let's do a quick review of something super important: Place Value! Who can remind us what hundreds, tens, and ones are? Why is knowing place value important when we're working with bigger numbers like 3-digit numbers?"
## Direct Instruction: Our Secret Weapon (5 minutes)
Teacher: (Display 3-Digit Word Problems Slide Deck - Slide 3) "Every good detective needs a secret weapon, right? Ours is called CUBES! This strategy will help us break down any word problem we face. Let's look at what each letter means:
* Circle the numbers. Why do you think circling the numbers is the first step?
* Underline the question. What are we trying to find out?
* Box the keywords. These are super important words that tell us if we need to add or subtract. Can you think of any words that might tell us to add? How about to subtract?
* Evaluate and strategize. This is where we decide: Are we adding or subtracting? What's our plan to solve it?
* Solve and check! We do the math and then make sure our answer makes sense. Always check your work!"
## Guided Practice: Solving Mysteries (8 minutes)
Teacher: (Display 3-Digit Word Problems Slide Deck - Slide 4) "Alright, Math Detectives, let's try solving one together using our CUBES strategy. Follow along with me!"
(Read the problem aloud: "Sarah collected 145 stickers, and her friend Tom collected 238 stickers. How many stickers do they have altogether?")
Teacher: "First, Circle the numbers. What numbers do you see? (Wait for response: 145 and 238)
Next, Underline the question. What is the question asking us? (Wait for response: How many stickers do they have altogether?)
Now, Box the keywords. What word in this problem tells us what to do? (Wait for response: altogether)
Based on 'altogether', should we Evaluate and strategize to add or subtract? (Wait for response: Add) Exactly! We're putting them together.
So, to Solve, we need to add 145 + 238. Who can tell me what 145 + 238 equals? (Guide students through the addition, focusing on place value. Write it out on the board if helpful.) So, they have 383 stickers altogether! Does that answer make sense? Is it reasonable?"
(Display 3-Digit Word Problems Slide Deck - Slide 5) "Let's try another one! This time, you guide me through the CUBES steps!"
(Read the problem aloud: "A baker made 367 cookies. He sold 125 cookies. How many cookies does he have left?")
Teacher: "What's the first step in CUBES? (Wait for response: Circle numbers: 367, 125)
What's next? (Wait for response: Underline the question: How many cookies does he have left?)
And then? (Wait for response: Box the keywords: left)
What does 'left' tell us to do? Add or subtract? (Wait for response: Subtract) Great job!
So, to Solve, we subtract 367 - 125. What do you get when you subtract 125 from 367? (Guide students through subtraction, borrowing if necessary.) So, the baker has 242 cookies left. Does that sound right?"
## Independent Practice: Detective Time! (5 minutes)
Teacher: (Display 3-Digit Word Problems Slide Deck - Slide 6) "You've done an amazing job with our guided practice! Now it's your turn to be true Math Detectives. I'm handing out a Word Problem Worksheet. Your mission is to solve each problem using our CUBES strategy. Remember to show your work clearly. I'll be walking around if you need any help or have questions. Good luck, detectives!"
## Conclusion: Case Closed! (2 minutes)
Teacher: (Display 3-Digit Word Problems Slide Deck - Slide 7) "Alright, Math Detectives, bring it back together! You've cracked some tough cases today! What was our secret weapon for solving word problems? (Wait for response: CUBES!) Why is the CUBES strategy helpful?
What's one new thing you learned or one strategy you'll remember when solving word problems with 3-digit numbers? Great job today everyone! Please turn in your worksheets as you leave. Case closed!"
Worksheet
Math Detective: 3-Digit Word Problems
Instructions: Read each word problem carefully. Use the CUBES strategy (Circle numbers, Underline the question, Box keywords, Evaluate, Solve and check) to help you solve. Show your work in the space provided.
---
### Problem 1
The school library has 352 fiction books and 219 non-fiction books. How many books does the library have altogether?
Show your work:
Answer:
---
### Problem 2
A farmer picked 487 apples. He sold 154 apples at the market. How many apples does he have left?
Show your work:
Answer:
---
### Problem 3
A bakery made 175 chocolate chip cookies and 230 oatmeal cookies. How many cookies did the bakery make in total?
Show your work:
Answer:
---
### Problem 4
There were 563 birds sitting on a tree. 231 birds flew away. How many birds are still on the tree?
Show your work:
Answer:
---
### Problem 5
Maria saved $120. Her grandmother gave her $250 more. How much money does Maria have now?
Show your work:
Answer:
---
### Challenge Problem!
A toy store had 345 toy cars. They received a new shipment of 180 toy cars. Then, they sold 115 toy cars. How many toy cars do they have now?
Answer Key
Answer Key: 3-Digit Word Problems
## Problem 1
The school library has 352 fiction books and 219 non-fiction books. How many books does the library have altogether?
Thought Process:
1. The keyword "altogether" indicates an addition problem.
2. Add the number of fiction books to the number of non-fiction books.
352 (fiction) + 219 (non-fiction) = ?
Solution:
<br/> 352<br/> + 219<br/> -----<br/> 571<br/>
Answer: The library has 571 books altogether.
---
## Problem 2
A farmer picked 487 apples. He sold 154 apples at the market. How many apples does he have left?
Thought Process:
1. The keyword "left" indicates a subtraction problem.
2. Subtract the number of apples sold from the total number of apples picked.
487 (picked) - 154 (sold) = ?
Solution:
<br/> 487<br/> - 154<br/> -----<br/> 333<br/>
Answer: The farmer has 333 apples left.
---
## Problem 3
A bakery made 175 chocolate chip cookies and 230 oatmeal cookies. How many cookies did the bakery make in total?
Thought Process:
1. The keyword "in total" indicates an addition problem.
2. Add the number of chocolate chip cookies to the number of oatmeal cookies.
175 (chocolate chip) + 230 (oatmeal) = ?
Solution:
<br/> 175<br/> + 230<br/> -----<br/> 405<br/>
Answer: The bakery made 405 cookies in total.
---
## Problem 4
There were 563 birds sitting on a tree. 231 birds flew away. How many birds are still on the tree?
Thought Process:
1. The keywords "flew away" and "still on the tree" indicate a subtraction problem.
2. Subtract the number of birds that flew away from the initial number of birds.
563 (initial) - 231 (flew away) = ?
Solution:
<br/> 563<br/> - 231<br/> -----<br/> 332<br/>
Answer: There are 332 birds still on the tree.
---
## Problem 5
Maria saved $120. Her grandmother gave her $250 more. How much money does Maria have now?
Thought Process:
1. The keyword "more" (in the context of being given more money) indicates an addition problem.
2. Add the money Maria saved to the money her grandmother gave her.
120 (saved) + 250 (given) = ?
Solution:
<br/> 120<br/> + 250<br/> -----<br/> 370<br/>
Answer: Maria has $370 now.
---
## Challenge Problem!
A toy store had 345 toy cars. They received a new shipment of 180 toy cars. Then, they sold 115 toy cars. How many toy cars do they have now?
Thought Process:
1. "Received a new shipment" indicates addition.
2. "Sold" indicates subtraction.
3. This is a two-step problem: first add, then subtract.
Step 1: 345 (initial) + 180 (new shipment) = ?
Step 2: (Result from Step 1) - 115 (sold) = ?
Solution:
<br/> Step 1: Step 2:<br/> 345 525<br/> + 180 - 115<br/> ----- -----<br/> 525 410<br/>
Answer: The toy store has 410 toy cars now.