enVision Mathematics Kindergarten, Topic 10: Composing/Decomposing Numbers 11 to 19
In this unit, your child looks inside the teen numbers. Kindergartners see that 15 is a full ten and 5 extra ones, build teen numbers with a filled ten-frame and leftovers, and write matching equations like 10 + 5 = 15. It gives meaning to the counting-to-20 work just finished, and this idea of tens and ones powers the next unit's counting all the way to 100.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Topic 10?
- Building numbers from 11 to 19 as ten ones and some more ones, and writing equations like 10 + 5 = 15 to match. Learn more: Teen numbers as ten and some more
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
What do 10 and 1 make?
- 10
- 11
- 12
How you can help
- Line up 10 spoons in a row and put a few more below them, then ask how many in all, saying it as ten and some more, like 10 and 3 make 13.
- Show 10 fingers, then have your child show some more fingers, and say the teen number you make together, like 10 and 6 make 16.
- Write a teen number, such as 17, and ask your child which part is the ten and which part is the extra ones, then build it with toys.
Where kids can get stuck
- Thinking the 1 in 16 means one object, so they show 16 with just 1 block and 6 blocks.
- Losing count while building the ten, so the group of ten ends up with 9 or 11 objects.
- Writing 13 = 10 + 3 but not linking the equation back to the objects they built.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- teen numbers
- The numbers 11 to 19, each made of ten and some more ones.
- ten ones
- Ten single things, which together make one ten.
- ones
- Single things counted one at a time.
- ten-frame
- A grid of 10 boxes, in two rows of 5, used to show numbers.
- equation
- A math sentence with an equal sign, like 3 + 2 = 5.
- digit
- One of the ten symbols, 0 to 9, used to write every number.
Ready to build your child’s confidence with teen numbers?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
Join the club
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does enVision Mathematics Kindergarten Topic 10 cover?
enVision Mathematics Kindergarten Topic 10 covers this math standard. Each one links to what it means, sample questions, and teaching strategies.
- K.NBT.A.1: Compose and decompose numbers 11-19.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.