Decomposing Numbers 10-20 Worksheet

Decomposing numbers is one of the biggest ideas a Kindergarten student meets in math, because it is the moment numbers stop being single labels and start being made of parts. This decomposing numbers 10-20 worksheet gives young learners a clear, hands-on way to see that every teen number is simply one full ten plus a few more ones. Using familiar ten frames, students count a complete group of ten, count the extra counters underneath, and then record what they see as an addition equation. That single move — picture to equation — is exactly what the Kindergarten standard asks for, and it builds the place value foundation that first and second grade addition depends on.

The worksheet is built for independent work and takes about ten minutes. The first four items show two ten frames that are already filled, so the student only needs to count carefully and finish the equation. The last item flips the task: the number 16 is given, and the student draws the counters themselves before writing the missing part. Print one copy per student, hand out real counters if you want a concrete warm up first, and use the included answer key to check the page in seconds. Every number on this decomposing numbers 10-20 worksheet stays inside the 10 to 20 range so the ten and some more pattern stays visible on every problem.

What’s Included

• One printable Kindergarten math worksheet in PDF format
• Four count-the-ten-frame problems using the numbers 13, 17, 15, and 19
• One draw-your-own-counters problem for the number 16
• Extra-large ten frames and wide writing lines sized for young hands
• A complete answer key on the final page

Three Reasons This Helps Kids

• It makes place value visible. Seeing a full ten frame beside a partial one turns 17 into ten and seven, which is the mental picture students carry into regrouping later.
• It links pictures to equations. Recording each ten frame as 10 + ___ = ___ teaches students to translate a model into number sentences, a skill every later word problem uses.
• It builds counting confidence. The final draw-it-yourself item asks students to produce the model instead of reading one, which shows you who truly understands the teen numbers.

Teacher and Parent Ideas

Use this page as a math center by pairing it with two-color counters and a laminated ten frame mat so students can build each number before they write it. In small groups, ask a student to say the equation out loud — “ten and three make thirteen” — while a partner points to the counters. At home, this kindergarten addition worksheet works well as a five-minute warm up before a counting game, or as a quick review sheet after a lesson on teen numbers. You can extend it easily by asking students to flip the page over and draw their own ten frames for 11, 14, and 18.

Related Resources

• Compose and Decompose Numbers 11-19 Activity
• Decomposing a Ten Frame Activity
• Using a Tens Frame to Show Addition Worksheet
• Adding 10 Song