Solved Exercises on Subtraction Word Problem Strategies in 1st Grade

Master subtraction word problem strategies: key techniques, problem solving methods, and visual approaches through these 3 detailed exercises.

Solution: Exercises 1 to 3
1 Key word identification strategy
Exercise 1
Use the key word strategy to solve:
"Lucy had 7 stickers. She gave 3 to her friend. How many stickers does Lucy have left?"
Definition:

Key word strategy: Identifying specific words in a word problem that indicate which mathematical operation to use. For subtraction, look for words like "left", "gave", "took", "less", "fewer", "remains", etc.

Key word strategy method:
  1. Read the problem carefully
  2. Circle or highlight key subtraction words
  3. Identify the numbers involved
  4. Set up the subtraction equation
  5. Solve the equation
  6. Check if the answer makes sense
left
gave
took
away
lost
sold
used
ate
"Lucy had 7 stickers. She gave 3 to her friend. How many stickers does Lucy have left?"
1
Key words: "gave" and "left" indicate subtraction
2
Numbers: Lucy started with 7 stickers, gave away 3
3
Equation: 7 - 3 = ?
4
Solution: 7 - 3 = 4
Start with 7
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Gave away 3
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Remain 4
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Step 1: Identify the key word "gave"

"Gave" means she took away stickers, so we subtract

Step 2: Identify the key word "left"

"Left" asks how many remain after taking away

Step 3: Set up the subtraction

Start with 7, subtract 3, find the answer

\(7 - 3 = 4\)
Final answer:

Lucy has 4 stickers left.

Applied rules:

• Key words: "gave" and "left" signal subtraction

• Problem structure: Start amount - taken away = remaining

• Visual method: Use objects to represent the problem

2 Draw a picture strategy
Exercise 2
Use the drawing strategy to solve:
"There were 9 birds on a branch. 4 flew away. How many birds are still on the branch?"
Definition:

Draw a picture strategy: Creating visual representations of the problem to understand and solve it. This helps visualize the subtraction process.

"There were 9 birds on a branch. 4 flew away. How many birds are still on the branch?"
1
Draw 9 birds to represent the starting amount
2
Cross out 4 birds to represent those that flew away
3
Count the remaining birds
4
Solution: 9 - 4 = 5
Start with 9
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4 flew away
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Remain 5
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Step 1: Identify the key phrase "flew away"

"Flew away" means birds left, so we subtract

Step 2: Draw the starting number

We draw 9 birds to represent the initial amount

Step 3: Show what was taken away

We cross out 4 birds to represent those that flew away

\(9 - 4 = 5\)
Final answer:

There are 5 birds still on the branch.

Applied rules:

• Key words: "flew away" signals subtraction

• Problem structure: Initial amount - amount removed = final amount

• Visualization: Drawing pictures helps understand the problem

3 Count backwards strategy
Exercise 3
Use the counting backwards strategy to solve:
"Tom had 6 cookies. He ate 2. How many cookies does Tom have now?"
Definition:

Count backwards strategy: Starting from the initial number and counting backwards by the number being subtracted. This is especially useful for small numbers.

"Tom had 6 cookies. He ate 2. How many cookies does Tom have now?"
1
Start at the initial number: 6
2
Count backwards by the number being subtracted: 2 steps
3
Count: 6, 5, 4 (stop after 2 steps)
4
Solution: 6 - 2 = 4
6
5
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Start with 6
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Ate 2
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Remain 4
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Step 1: Identify the key word "ate"

"Ate" means Tom took away cookies, so we subtract

Step 2: Start counting backwards from 6

We start at 6 and count backwards 2 steps

Step 3: Count backwards: 6, 5, 4

We stop after 2 steps and land on 4

\(6 - 2 = 4\)
Final answer:

Tom has 4 cookies now.

Applied rules:

• Key word: "ate" signals subtraction

• Counting backwards: Move left on the number line

• Subtraction: Each step backward represents taking away 1

Subtraction Word Problem Strategies
\( \text{Strategy} \rightarrow \text{Solution} \)
Effective Approaches
Key Word Strategy

This strategy focuses on identifying specific words that signal subtraction operations.

Step 1: Read the problem carefully and circle key subtraction words
Step 2: Identify the numbers involved in the subtraction
Step 3: Set up the subtraction equation
Step 4: Solve and check if the answer makes sense
Example: "She had 8 apples and gave 3 away. How many left?" → "gave" and "left" indicate subtraction
Draw a Picture Strategy

This strategy uses visual representations to understand and solve the problem.

Step 1: Draw objects to represent the starting amount
Step 2: Cross out or remove the number being subtracted
Step 3: Count the remaining objects
Step 4: Write the subtraction equation
Example: For 7 - 2, draw 7 circles, cross out 2, count 5 remaining
Count Backwards Strategy

This strategy involves counting backwards from the starting number by the amount being subtracted.

Step 1: Start at the initial number
Step 2: Count backwards by the number being subtracted
Step 3: Stop after counting the required number of steps
Step 4: The number you land on is the answer
Example: For 8 - 3, count backwards: 8, 7, 6, 5 → answer is 5
Finger Counting Strategy

This strategy uses fingers to physically represent and solve the subtraction problem.

Step 1: Hold up fingers to match the starting number
Step 2: Put down fingers equal to the number being subtracted
Step 3: Count the remaining fingers
Step 4: That's your answer
Example: For 6 - 2, hold up 6 fingers, put down 2, count 4 remaining
When to Use Each Strategy:
  • Key Word Strategy: When you can identify clear subtraction words
  • Draw a Picture: When visualizing helps you understand the problem
  • Count Backwards: When working with small numbers
  • Finger Counting: When you need physical manipulation
Strategy Selection Tips:

• Try different strategies: Find the one that works best for you

• Combine strategies: Use multiple approaches to verify your answer

• Practice regularly: The more you practice, the better you'll become

Advanced Problem Solving Strategies
\( \text{Multiple Strategies} \rightarrow \text{Better Understanding} \)
Combining Techniques
Multi-Step Problem Strategy

For problems that require multiple subtraction operations, solve one step at a time.

Step 1: Identify each separate subtraction needed
Step 2: Solve the first subtraction operation
Step 3: Use the result as the starting point for the next operation
Step 4: Continue until all operations are completed
Example: "Sarah had 10 stickers. She gave 3 to Tom and 2 to Jane. How many left?" → 10 - 3 = 7, then 7 - 2 = 5
Verification Strategy

Always check your answer to make sure it makes sense in the context of the problem.

Step 1: Add your answer back to the subtracted number
Step 2: Compare with the original number
Step 3: Check if the answer fits the story
Step 4: Make sure your answer is less than the starting number
Example: If 8 - 3 = 5, check: 5 + 3 = 8 ✓
Think Addition Strategy

Use addition facts to help solve subtraction problems.

Step 1: Think "What number added to the subtracted number equals the starting number?"
Step 2: Use known addition facts to find the answer
Step 3: Apply the relationship: If a + b = c, then c - a = b
Step 4: Use this to verify your subtraction answer
Example: For 7 - 3 = ?, think "3 + ? = 7", so ? = 4
Tip 1: Use the strategy that feels most comfortable to you initially.
Tip 2: Try different strategies for the same problem to verify your answer.
Tip 3: Practice with real-life scenarios to build understanding.
Tip 4: Always check if your answer makes sense in the story.
Common errors: Misreading key words, subtracting in the wrong direction, forgetting to identify all numbers in multi-step problems.
Success strategies: Circle key words, underline numbers, draw pictures, check answers.
Advanced problem-solving concepts:

• Subtraction means taking away or finding the difference

• Always check if your answer makes sense in the story

• Some problems have multiple steps requiring several operations

• Combine strategies for complex problems

Detailed Summary: Subtraction Word Problem Strategies
Complete Learning Guide
Definition of Subtraction Word Problem Strategies: Systematic approaches to solving subtraction word problems by identifying key words, using visual representations, and applying logical reasoning to convert word problems into mathematical expressions.
Key Terms:
  • Key Word Strategy: Identifying specific words that signal subtraction operations
  • Draw a Picture Strategy: Creating visual representations of the problem
  • Count Backwards Strategy: Moving backwards on a number line
  • Finger Counting Strategy: Using fingers to physically solve the problem
  • Multi-Step Strategy: Solving problems with multiple operations
  • Verification Strategy: Checking if the answer makes sense
Core Rules of Problem Solving:
  • Key Word Recognition: Words like "left", "gave", "took", "away" indicate subtraction
  • Visual Representation: Drawing pictures helps understand the problem
  • Sequential Processing: Solve multi-step problems one operation at a time
  • Verification: Always check if the answer fits the story context
Main Strategies:
  1. Key Word Strategy: Identify words that signal subtraction (left, gave, took, away, etc.)
  2. Draw a Picture: Create visual representations of the problem
  3. Count Backwards: Move backwards on the number line
  4. Finger Counting: Use fingers to physically solve
  5. Think Addition: Use addition facts to help with subtraction
Examples (Simple to Advanced):
  • Simple: "I had 5 apples and ate 2. How many are left?" (Key word strategy: ate → subtract)
  • Medium: "There were 8 cars in the parking lot. 3 drove away. How many remain?" (Picture strategy: draw 8, cross out 3)
  • Advanced: "Sarah had 10 stickers. She gave 2 to Mike and 3 to Jane. How many does she have left?" (Multi-step: 10 - 2 - 3 = 5)
Tips and Tricks:
  • Create a personal list of subtraction key words to remember
  • Always reread the problem after solving to check your answer
  • Draw simple pictures to visualize the problem situation
  • Check your answer by adding it back to the subtracted amount
  • Pay attention to the order of operations in multi-step problems
Common Pitfalls:
  • Misidentifying key words and using the wrong operation
  • Forgetting to consider all parts of multi-step problems
  • Subtracting in the wrong direction (smaller from larger)
  • Not checking if the answer makes sense in the context
Memory Aids:
  • "Subtraction words often describe things going away!"
  • "Look for words about giving, taking, losing, or spending!"
  • "Questions about 'how many left' usually mean subtract!"
  • Practice with real-life scenarios to build understanding
Checking Your Work: Always verify your answer makes sense in the story. For example, if you started with 7 items and some were taken away, your answer should be less than 7.

Questions & Answers

Question: I know the key words strategy, but sometimes I see words like "more" and "total" in subtraction problems. How do I know which strategy to use?

Answer: Great observation! Some words can be tricky. Here's how to handle them:

  • Context matters: "More" usually means addition, but "how many more" often means subtraction (finding the difference)
  • "Total" is flexible: Usually addition, but in problems like "total number left", it means subtraction
  • Focus on the question: What is the problem asking? "How many are left?" almost always means subtraction
  • Combine strategies: Use key words AND draw a picture to understand the situation
  • Read the whole problem: Don't just look for keywords, understand the entire story

Example: "Sarah has 5 apples. Tom has 3 apples. How many more apples does Sarah have than Tom?" → "how many more" means subtraction: 5 - 3 = 2

Remember: Keywords are helpful but not always definitive - always consider the context!

Question: I really like the drawing strategy, but sometimes I draw the wrong number of things. How can I make sure I draw the right amount?

Answer: That's a common challenge! Here are tips to make your drawings more accurate:

  • Count as you draw: Say the numbers out loud as you draw each item (one, two, three...)
  • Organize your drawing: Arrange items in rows or groups to make counting easier
  • Double-check: After drawing, count again to make sure you have the right number
  • Use simple symbols: Circles, squares, or X's work just as well as detailed drawings
  • Label your drawing: Write the number next to your drawing to remind yourself

Example: If you need to draw 7 apples, draw them in a row and count: 1, 2, 3, 4, 5, 6, 7. Then count again to verify!

The drawing strategy is very effective once you get the counting right - keep practicing!

Question: I'm getting better at subtraction word problems, but I still sometimes get confused about which number to start with. How do I figure that out?

Answer: That's a very common challenge! Here's how to identify the starting number:

  • Look for "had", "started with", "were", "is": These often introduce the starting number
  • Think about the story: What did the person or situation have at the beginning?
  • Ask yourself: "Before anything happened, how many were there?"
  • Underline the starting amount: Mark it clearly when reading the problem
  • Picture the scene: Imagine what the situation looked like at the start

Example: "Emma had 8 balloons. She gave 3 to her friend." → "had 8" tells you the starting number is 8

Another example: "There were 6 birds on the tree. 2 flew away." → "were 6" tells you the starting number is 6

The starting number is always the amount before any subtraction happens!