Math Expressions Grade 1, Unit 5: Place Value Word Problems and 2-Digit Addition
In this unit, your child uses tens and ones to solve word problems and add two-digit numbers, making a new ten when the ones add up to 10 or more. They also find 10 more and 10 less and subtract tens. This follows the place value unit and leads into geometry, time, and equal shares.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 5?
- Solving word problems and adding within 100, such as 28 + 5 or 24 + 30, by adding tens and ones separately. Learn more: Adding two-digit numbers within 100
- Finding 10 more and 10 less than a number mentally, and spotting that only the tens digit goes up or down. Learn more: 10 more or 10 less in your head
- Subtracting tens, like 60 - 20, by thinking about tens, and checking the answer with addition. Learn more: Subtracting tens, like 70 - 30
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
- Tell a word problem while putting groceries away: "There are 28 crackers in this box and 5 in that one. How many in all?" Ask your child to explain how they made a new ten.
- Play 10 more on a walk or ride: say a number like 43 and have your child answer 53, then 63, as fast as they can.
- Draw 6 ten-sticks and cross out 2. Ask your child how many tens are left and what number that is.
Where kids can get stuck
- Adding the 5 to the tens in 28 + 5, getting 78 instead of 33.
- Getting stuck at the ends, like 10 less than 15, where the answer has fewer digits.
- Counting back by ones from 60 for 60 - 20, instead of counting back by tens: 50, 40.
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
- tens
- Groups of ten. In 34, the 3 means 3 tens.
- ones
- Single units. In 34, the 4 means 4 ones.
- new ten
- Ten ones grouped together to make one ten when adding.
- sum
- The answer when you add numbers together.
- 10 more
- The number you get by adding one ten, like 47 to 57.
- 10 less
- The number you get by taking away one ten, like 47 to 37.
- difference
- The answer when you subtract one number from another.
Want to help your child master two-digit addition?
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 Math Expressions Grade 1 Unit 5 cover?
Math Expressions Grade 1 Unit 5 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.