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Addition within 20 worksheets

Twenty addition facts with sums up to 20, in three versions with keys. Includes the facts that bridge past 10, like 8 + 5, which are the ones children find hardest.

Addition: within 20

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Sheet AFree at teach.peabody.kids

Addition: within 20

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Sheet BFree at teach.peabody.kids

Addition: within 20

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Sheet CFree at teach.peabody.kids

Answer key

Sheet A

  1. 20
  2. 18
  3. 18
  4. 9
  5. 17
  6. 14
  7. 19
  8. 16
  9. 11
  10. 10
  11. 19
  12. 18
  13. 20
  14. 13
  15. 20
  16. 20
  17. 18
  18. 11
  19. 12
  20. 13

Sheet B

  1. 17
  2. 15
  3. 13
  4. 18
  5. 4
  6. 11
  7. 8
  8. 19
  9. 14
  10. 16
  11. 16
  12. 6
  13. 20
  14. 19
  15. 16
  16. 7
  17. 12
  18. 13
  19. 20
  20. 18

Sheet C

  1. 20
  2. 10
  3. 14
  4. 16
  5. 12
  6. 14
  7. 20
  8. 19
  9. 19
  10. 9
  11. 14
  12. 10
  13. 19
  14. 10
  15. 20
  16. 11
  17. 13
  18. 20
  19. 15
  20. 15
Answer keyFree at teach.peabody.kids

Addition: 20 problems a sheet, 3 versions that do not repeat each other where the numbers allow.

How to use it

  1. Look at the sheet: it is a real, printable sheet. Switch between Sheet A, B and C, or press New numbers (N) for a fresh set.
  2. Change how many problems, how many versions, and whether the key prints. Settings stay in this browser; Share copies a link that rebuilds the same sheets.
  3. Press Print sheet A and key, or Print all. The answer key prints on its own page, so you can keep it back.

Ideas for class

  • Mark the facts that cross ten with a small dot on your copy of the key, then circle them on a student's sheet to find where they stall.
  • Use the three versions across a week: A on Monday, B on Wednesday, C on Friday, with the same time limit, so any progress is real and the numbers are never memorized as a page.
  • Turn on the on-a-line layout once the stacked version is easy, so students see addition as a sentence, not only as a column.

Related

Questions

How is this different from the within 10 sheet?

The within 10 sheet stops at a sum of 10. This one goes up to 20, so many problems need a ten to be bridged. It is the next sheet to use once the first is quick.

Can I limit it to facts that cross ten?

Open the sheet in the maker and set Regrouping to Always regroup. That keeps only the facts whose ones add to ten or more, such as 8 + 5, and leaves out the easy ones.

Are the answer keys checked?

Each answer is worked out by the code that wrote the problem, and our tests recompute every answer a second way and compare. Please still look over the key before you grade a class set.

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What this worksheet covers

This sheet covers every addition fact whose sum is 20 or less. Some are easy, such as 12 + 3 or 6 + 6. Others cross ten, such as 9 + 7 or 8 + 5, and these are the facts that take real practice. Because the sheet draws at random from all of them, a student meets both kinds, and the keys let you see at a glance which kind caught them out.

Who it is for

First grade builds toward this, and second grade expects it to be automatic. Common Core 2.OA.B.2 says that by the end of grade 2 children should know from memory all sums of two one-digit numbers, which is the heart of this sheet.

Adding two numbers with a sum of 20 or less · grades 1 and 2

A worked example

For 8 + 5, one strategy is to make ten: take 2 from the 5 to fill the 8 up to 10, which leaves 3, so the answer is 13. Ask students to say the first step aloud before they write anything, and to try the same move on 9 + 4 and 7 + 6.

Mistakes to watch for

  • Treating 10 as a barrier and answering 8 + 5 with 12 or 14. A ten frame or a number line to 20 shows the crossing.
  • Reversing digits in teen answers, writing 31 for 13. Say the number aloud as you write it, ten and three.

Make it your own

This sheet is one setting of the math worksheet generator. Open it there to change the skill, the range of numbers or the heading, or to mix several skills on one sheet.