First Grade Adding Within Twenty Challenge

Counters, number lines, and ten frames . . . oh my!  It's the beginning of spring and if you are a first grade educator you might be celebrating because your students have finally mastered basic addition facts.  In Virginia, the old standards required the children to add within ten.  This was easy for many students to do.  Little fingers were always on hand (pardon the pun).  The children could easily use them as their "manipulatives" to check and confirm sums when adding.  In 2012, new standards were adopted in Virginia.  Currently, Virginia first graders are required to add within eighteen.  Little folks in states that have adopted the Common Core Standards must add within twenty!  Additionally, it is not enough to simply add two addends and find the sum.  Students are also required to balance equations, find a missing addend (when the sum is given), add three addends to find a sum, add in horizontal form, add in vertical form and the list goes on.

Adding with zero strategy in vertical form.  I decided to use the zero for the second addend throughout all of the problems on the page shown above.  Some students get confused with adding zero!  Students glue the eggs where indicated with the appropriate sum creating a flap that can be raised to view the answers. 

 With such a demanding standard placed on little kids, counters, number lines, and ten frames are essential in every first grade classroom.  But it is also necessary for educators to teach children to use mental math strategies and learn a few other "tricks" in order for the"Within Twenty" challenge to successfully be achieved.  For this post, I am focusing on strategies for math problems with two addends with a missing sum. 

An easy strategy to start with is the "Count On" strategy.  When one of two addends is the number one, "Count on one more."  For students to apply this strategy, they will need to be able to count by ones up to twenty.  If students can't count by ones to twenty, this strategy will not be useful.

Another strategy requires that students learn how to skip count to 20.  The skip counting strategy can be applied with addition problems when one of the two addends is the number two.  First graders will need to be taught how to apply the strategy.  Before the strategy can be utilized, they need to have these two counting sequences memorized:

0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20

and

  1, 3, 5, 7, 9, 11, 13, 15, 17, 19

Children can also look for interesting patterns in addition facts.  For instance, doubles facts (which use two addends) will always result in an even number for its sum.  (1 + 1 = 2, 2 + 2 = 4, 3 + 3 = 6, 4 + 4 = 8, 5 + 5 = 10 . . .)  This will assist a child when he checks his work.  If he adds "seven plus seven" and gets fifteen, he should be able to identify the error.  None of this will be helpful unless the child knows his odd and even numbers up through twenty.  If the teacher plans to teach the skip counting strategy, she can teach the odd and even numbers at the same time.  Maybe it would look something like this:

Let's Skip Count Our Even Numbers:

  0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20

Let's Skip Count Our Odd Numbers:

  1, 3, 5, 7, 9, 11, 13, 15, 17, 19

For differentiated learners, a chart which displays the odd and even numbers through twenty might be appropriate instead of memorization.

Another interesting pattern that the educator can lead her students to discover is doubles facts which use three addends.  These will result in a "like" sum.  Three even numbered addends will result in an even numbered sum.  Three odd numbered addends will result in an odd numbered sum.  (0 + 0 + 0 = 0, 1 + 1 + 1 = 3, 2 + 2 + 2 = 6, 3 + 3 + 3 = 9, 4 + 4 + 4 = 12)

There are nearly endless strategies that can be taught.  When given the opportunity, children can also discover many addition patterns on their own.  Taking the time to teach the skills needed for the strategies and teaching their applications, can make the "Within Twenty Challenge" a little easier to accomplish. 

The glue is affixed to the top of the egg with the sum so the top egg acts as a flap to reveal the answers underneath.

I have created a few printable worksheets that may help in reaching this important math standard.  It's just in time for spring and Easter! 


I've included rabbit counters, number lines, and ten frames.  There is also a cover page that can be stapled to the top of the completed pages to make a booklet for the children to recall the facts with.

This product is called, "Sum Bunny Knows Addition Facts" packet.  A cute rabbit prompts the children to recall mental math strategies to solve addition facts.  Yes, the rabbit knows a few tricks!  The addition facts that are printed on the eggs are in vertical and horizontal form.  The children cut the eggs out and partially glue them to the appropriate sums creating a flap.  The teacher determines which format (horizontal or vertical) to use for each page.  Print the vertical format, or the horizontal format, or a mix of the two.  Use the ones that suit your individual classroom needs!

There are pages for each:  Adding zero, adding one, adding two, adding with nine, adding within 10, adding within 20, and doubles facts.  There is also a certificate of accomplishment with two blank lines - one for the student's name and one for the teacher's name.

I also added a sized-down version of the packet that will allow the pages to fit inside of composition books.  The sized down version is include in the packet itself so that you will have both options available to you.  The number lines and ten frames will work fine with the composition books.  The eggs on the scaled down version are very small and some first graders will have difficulty cutting them out.  Assistance will be required for those students.

The children can color the eggs lightly prior to cutting them out.  Cutting out the eggs for the composition book will NOT be as easy as it looks!  This is what I perceive as one of the down sides to the composition book size.  It's easier with the full sized sheets.  Additionally, glue or staples will be required to secure the sheets to the composition books.

This is one of the scaled down printables for student composition books.  The smaller sized sheets can be glued or stapled inside the composition books.  The plus side of the composition books is that it provides the teacher and the student with the record of the work which is easy to keep organized.

This packet is available at my TeacherspayTeachers shop.  Click on the picture below to view the product at my TpT store.  

Here's what is included in the file: 

1. Cover sheet for making a book with the sheets if desired

2. Certificate of completion

3. Adding with zero eggs - horizontal format

4. Adding with zero eggs - vertical format

5. Adding with zero page

6. Adding with one eggs - horizontal format

7. Adding with one eggs - vertical format 

8. Adding with one page

9. Adding with two eggs - horizontal format

10. Adding with two eggs - vertical format

11. Adding with two page

12. Doubles facts eggs - horizontal format

13. Doubles facts eggs - vertical format

14. Doubles facts page

15. Adding with nine eggs - horizontal format

16. Adding with nine eggs - vertical format

17. Adding with nine page

18. Adding within ten eggs - horizontal format

19. Adding within ten eggs - vertical format

20. Adding within ten page

21. Adding within ten page (alternate model)

22. Adding within twenty eggs - horizontal format

23. Adding within twenty eggs - vertical format

24. Adding within twenty page

25. Double Ten Frame Mat

26. Rabbit Counters

27. Rabbit Counters (Color Edition)

28. Numbered Number-line - With an image of a boy

29. Numbered Number-line - With an image of a girl

30. Blank Number-line - With an image of a boy

31. Blank Number-line - With an image of a girl

Lessons by Molly © 2014  All rights reserved.