enVision Mathematics Grade 1, Topic 10: Use Properties to Add Tens and Ones
In this unit, first graders add within 100, putting tens with tens and ones with ones, and making a new ten when the ones add up to 10 or more. They add in whichever order is easiest and find 10 more or 10 less than a number in their heads. It builds on comparing two-digit numbers from the last unit and prepares them for subtracting tens next.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Topic 10?
- Adding numbers like 36 + 7 and 45 + 30 by combining tens with tens and ones with ones, making a new ten when needed. Learn more: Adding two-digit numbers within 100
- Finding 10 more or 10 less than a two-digit number in their heads, knowing only the tens digit changes. Learn more: 10 more or 10 less in your head
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
If you have 2 tens and 4 ones, and then you get 5 more ones, how many do you have in total?
- 30
- 29
- 28
How you can help
- Add two small prices together at the store, like 24 cents and 30 cents. Ask your child to add the tens first, then the ones.
- Make a number with bundles of ten and loose straws, like 36, then add 7 loose straws. When there are 10 loose ones, bundle them into a new ten.
- Play "10 more" on a walk: you say a number, like 58, and your child says 68. Switch to 10 less and take turns.
Where kids can get stuck
- Answering 38 for 36 + 20, treating 20 as if it were 2.
- Writing 313 for 36 + 7 instead of making a new ten from the 13 ones.
- Saying 10 more than 34 is 35, changing the ones digit.
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
- add
- Put amounts together to find how many in all.
- tens
- Groups of ten. In 34, there are 3 tens.
- ones
- Single things not in a group of ten. In 34, there are 4 ones.
- sum
- The answer when you add, like 7 in 3 + 4 = 7.
- make a ten
- Split a number to fill a ten first, like 8 + 5 = 8 + 2 + 3.
- 10 more
- The number you get by adding one ten, like 46 to 56.
- 10 less
- The number you get by taking away one ten, like 46 to 36.
Want to help your child master adding two-digit 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.
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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 Grade 1 Topic 10 cover?
enVision Mathematics Grade 1 Topic 10 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
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.