MathIsimple
Unit 2: Lesson 3

Subtraction Strategies within 20

Harvest subtraction mastery! Learn powerful strategies like count back, think addition, and fact families. Become confident at subtracting numbers up to 20!

40-50 min
Medium
Count Back
Think Addition
Fact Families
Mental Subtraction

🌿 Strategy Garden - Subtraction Edition!

Prune and perfect your subtraction skills with these interactive strategy builders!

Count Back on Number Line

Drag the jump arrows to count back!

Medium
6 minutes
📉

14 - 5 = ? Drag the jump arrow to the correct position (jump back 5 times from 14)

🖱️ Drag options below to the correct boxes (computer) or click to move (mobile)

📍 Target Zones

📏Jump back 5 from 14
Waiting...
Final Answer
Waiting...

🎯 Draggable Options

🦘↶ -5
🎯9
Progress:
0 / 2
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Think Addition!

Use addition to solve subtraction!

Medium
5 minutes
🧠

13 - 8 = ? Hint: Think about 8 + ___ = 13

Click to interact →

Choose the Fact Family

Which facts belong to the same family?

Medium
5 minutes
👨‍👩‍👧

Which group of equations belongs to the same Fact Family?

Click to interact →

Which Strategy Works?

Click all good subtraction strategies!

Easy
5 minutes
🎯

Click all strategies that can solve 12 - 7

Click all correct options

Selected: 0
Click to interact →

Master These 8 Subtraction Strategies

Learn smart strategies that make subtraction easy and fun! Each strategy is a powerful tool in your math garden.

1

Count Back Strategy

Count Back means starting at the bigger number and counting DOWN! To subtract, hop backwards on your number path. Like climbing down stairs - start at the top, count your steps down!

💡 Imagine standing on step 15, then counting backwards 3 steps: 14... 13... 12! You land on 12!

🌟Examples:

🔙

Simple Count Back

15 - 3: Start at 15, count back 3: '14, 13, 12!' Answer is 12!

🚗

Toy Cars

You have 11 cars, give away 2. Count back from 11: '10, 9!' You have 9 cars left!

🍪

Cookies on Plate

13 cookies - eat 4. Count back: '12, 11, 10, 9!' You have 9 cookies!

Sticker Collection

18 stickers - give 3 away. Count back: '17, 16, 15!' You have 15 left!

📚

Books on Shelf

14 books - borrow 2. Count back: '13, 12!' You have 12 books!

Common Mistake Alert! ⚠️

Counting back too many or too few! Use your fingers to track how many times you count back.

2

Think Addition (The Opposite Trick!)

Think Addition means using ADDITION to solve subtraction! Instead of 12-5=?, think 'What + 5 = 12?' The answer is 7! It's like solving a puzzle - find the missing piece!

💡 Imagine a puzzle: You have 12 pieces total, 5 are here, how many are missing? Same as 12-5!

🌟Examples:

💡

The Classic 13 - 6

Think: 'What plus 6 equals 13?' Answer: 7! So 13-6=7!

🎁

Toy Mystery

Box holds 15 toys, 8 are here. How many missing? Think: 8+?=15. Answer: 7!

🍎

Apple Basket

Started with 17 apples, 9 left. How many eaten? Think: 9+?=17. Answer: 8 eaten!

💰

Money Problem

Had 14 dollars, 6 dollars remain. How much spent? Think: 6+?=14. Spent 8 dollars!

Common Mistake Alert! ⚠️

Forgetting to flip the question! 'What plus [small number] makes [big number]?'

3

Use Ten Strategy

Use Ten means subtracting TO 10 first, then subtracting the rest! Break the subtraction into two easy steps. Get to 10 (the friendly number), then keep going!

💡 Think of 10 as a rest stop on your journey - stop there first, then finish the trip!

🌟Examples:

🎯

The 15 - 7 Example

15-5=10 (get to 10), then 10-2=8. Total: 15-7=8! Broke 7 into 5+2!

Marble Collection

13 marbles - 5 marbles. First 13-3=10, then 10-2=8. You have 8 marbles!

🖍️

Crayon Box

16 crayons - 8 crayons. First 16-6=10, then 10-2=8. You have 8 crayons!

Sticker Pages

14 stickers - 6 stickers. First 14-4=10, then 10-2=8. You have 8 stickers!

Common Mistake Alert! ⚠️

Not breaking the number correctly! Figure out how much to get to 10 first, then subtract the rest.

4

Subtract in Parts

Subtract in Parts means breaking the number you're subtracting into easier chunks! Like eating a big sandwich in small bites. Subtract piece by piece until you're done!

💡 Think of it like stepping down a staircase - take one step at a time instead of jumping!

🌟Examples:

🧩

Breaking 7 Apart

15-7: Break 7 into 5+2. First 15-5=10, then 10-2=8! Answer: 8

🧸

Toy Give-Away

12 toys - 8 toys. Break 8 into 2+6. First 12-2=10, then 10-6=4. You have 4 toys!

🍪

Cookie Jar

18 cookies - 9. Break 9 into 8+1. First 18-8=10, then 10-1=9 cookies left!

✏️

Pencil Count

16 pencils - 7. Break 7 into 6+1. First 16-6=10, then 10-1=9 pencils!

Common Mistake Alert! ⚠️

Losing track of parts! Make sure you subtract ALL the pieces you broke the number into.

5

Number Line Jumps Backwards

A number line helps you SEE subtraction! Start at the first number and jump BACKWARD. Subtracting 14-5? Start at 14, make 5 hops backward, land on 9! Jump back to subtract!

💡 Imagine a path with numbers - jump backwards like a frog hopping away from higher numbers!

🌟Examples:

🐸

Jumping Back by Ones

11 - 4: Start at 11, jump back: 10, 9, 8, 7. You land on 7!

🦘

Big Jump Backwards

18 - 10: Start at 18, make one BIG backward jump of 10, land on 8! Easy!

🎲

Board Game Penalty

You're on space 15, go back 6 spaces: 14, 13, 12, 11, 10, 9! New space: 9!

🪜

Steps Counting Down

Start at step 17, go down 8 steps. Count back: you end up on step 9!

Common Mistake Alert! ⚠️

Counting the starting number as a jump! Start AT the first number, then jump backward.

6

Fact Families: The Number Triangle!

Fact Families are groups of related addition and subtraction facts using the SAME three numbers! Like a family living in one house. If you know 7+5=12, you also know 5+7=12, 12-7=5, and 12-5=7!

💡 Think of three numbers as best friends - they hang out together in four different ways!

🌟Examples:

👨‍👩‍👦

The 3, 5, 8 Family

3+5=8, 5+3=8, 8-3=5, 8-5=3. All use numbers 3, 5, and 8!

🧸

Toy Example

4 red toys + 9 blue toys = 13 toys. So 13-4=9 and 13-9=4. Same family!

🏠

The 6, 7, 13 Family

6+7=13, 7+6=13, 13-6=7, 13-7=6. Four facts from three numbers!

🍎

Apple Math

8+6=14 apples. So 14-8=6 and 14-6=8. Addition helps subtraction!

Common Mistake Alert! ⚠️

Not seeing the connection between addition and subtraction! They're partners, not separate!

7

Related Facts Speed Trick

Related Facts are fact families you know super well! When you master one addition fact, you instantly know TWO subtraction facts! It's like getting three answers for the price of one!

💡 It's like having a magic key that opens three doors at once!

🌟Examples:

Double Power

Know 8+8=16? Then you know 16-8=8 for FREE! Doubles make subtraction easy!

🧠

Quick Recall

Memorize 9+7=16, and 16-9=7 plus 16-7=9 come automatically! Three for one!

Sticker Smart

If 5+9=14 stickers, then 14-5=9 and 14-9=5 instantly! Lightning fast!

🎯

Game Points

7+6=13 points scored means 13-7=6 and 13-6=7. All connected!

Common Mistake Alert! ⚠️

Not practicing related facts together! Learn them as families, not isolated facts.

8

Mental Subtraction Mastery

Mental Subtraction means solving in your HEAD by choosing the SMARTEST strategy! Count back for small numbers, think addition when it's easier, use 10 when helpful. You're the strategy boss!

💡 Your brain is a strategy toolbox - pick the perfect tool for each subtraction problem!

🌟Examples:

🧠

Choosing Strategies

14-2? Count back! 15-7? Use 10! 13-6? Think addition! Pick wisely!

💨

Subtracting 10

Any number - 10? Just change the tens place! 17-10=7, 19-10=9. Super quick!

🎭

Subtracting 9 Trick

Subtracting 9? Subtract 10, then add 1 back! 15-9 = 15-10+1 = 5+1 = 6!

💰

Shopping Change

Paid $20 for $13 toy. Think addition: 13+?=20. Need $7 change! Mental math wins!

🦸

Practice Makes Perfect

The more you practice, the faster you get! Your brain builds subtraction superpowers!

Common Mistake Alert! ⚠️

Using the hardest strategy! Always look for the easiest path to the answer.

Ready to Practice Subtraction Strategies?

Test your subtraction mastery with practice problems!

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