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Subtraction within 20 with place value transition (bridging through ten)

Mathematics Grade 1 Difficulty 3/5

Beginning of the lesson

Breaking Through Ten

What You Already Know: You can subtract numbers like 9 - 4 and 15 - 3. Now we learn something new!

What is "Breaking Through Ten"?

Sometimes when we subtract, we need to go back through 10. This is like crossing a bridge!

Example: 13 - 5

We start at 13. We need to take away 5.

But 13 only has 3 ones! We need to take 5 away!

So we must break apart the ten!

How to Break Through Ten

Step 1: See the Ten and Ones

TEN3 ones13 = 10 + 3

Step 2: Subtract to Get to 10 First

To subtract 5 from 13, first take away the 3 ones.

TENTake away 313 - 3 = 10

Step 3: Subtract the Rest from 10

We took away 3. We still need to take away 2 more. (Because 5 = 3 + 2)

Take away 2 more10 - 2 = 8Answer: 13 - 5 = 8

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In the full lesson

  • The complete explanation
  • Worked examples
  • Common mistakes and how to avoid them
  • Test questions: 45
  • AI tutor that answers questions about the topic
  • Progress tracking for students, parents and teachers