Eureka Math Grade 1, Module 2: Place Value Through Addition/Subtraction Within 20
In this unit, first graders add and subtract within 20 by making ten, seeing each teen number as a ten and some ones, the start of place value. They solve story problems, including ones that add three numbers, and add in an order that makes ten first. This grows from the facts within 10 in the last unit. Next, they compare and order lengths as numbers.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Module 2?
- Solving adding and subtracting stories within 20, using a ten and some ones to keep track of the amounts. Learn more: Adding and subtracting story problems within 20
- Adding three numbers in a story problem, looking for two that make ten first, like 7 + 5 + 3. Learn more: Story problems that add three numbers
- Regrouping addends to make ten, so 9 + 6 becomes 9 + 1 + 5, which is 10 + 5. Learn more: Adding in any order to make it easier
- Subtracting from teen numbers by taking from the ten, such as 13 - 9 = 10 - 9 + 3. Learn more about adding within 20: Adding within 20 · Learn more about subtracting within 20
- Seeing 10 as a bundle of ten ones and teen numbers as a ten and some ones, like 16 as 10 and 6. Learn more: Tens and ones in two-digit numbers
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
I had some toy cars. My friend gave me 3 more cars. Now I have 8 cars in total. How many toy cars did I have at first?
- 3
- 5
- 8
How you can help
- Set out 9 spoons and 6 forks. Move one fork next to the spoons to make a group of 10, then ask what 10 + 5 is and why it matches 9 + 6.
- Tell a story with three groups: "3 apples, 7 bananas, and 2 pears. How many pieces of fruit?" Ask which two your child added first, and why.
- Show a teen number with a bundle of ten straws and some loose ones, and ask your child to say it as tens and ones, like "1 ten and 6 ones is 16."
Where kids can get stuck
- Turning 8 + 5 into 8 + 2 + 2, splitting the 5 wrongly when making ten.
- Seeing 16 as a number to count up to rather than a ten and 6 ones.
- Trying to take 9 from the 3 ones in 13 and getting stuck, instead of taking from the ten.
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
- ten
- A group of ten ones.
- ones
- Single things not in a group of ten. In 34, there are 4 ones.
- teen number
- A number from 11 to 19, made of one ten and some ones.
- make a ten
- Split a number to fill a ten first, like 8 + 5 = 8 + 2 + 3.
- addend
- A number being added, like 3 and 4 in 3 + 4.
- place value
- What a digit is worth because of its spot, like the 4 in 42 meaning 40.
- total
- How many there are altogether.
Want to help your child master making ten?
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 Eureka Math Grade 1 Module 2 cover?
Eureka Math Grade 1 Module 2 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 1.OA.A.1: Use addition and subtraction within 20 to solve word problems.
- 1.OA.A.2: Solve word problems that call for addition of three whole numbers.
- 1.OA.B.3: Apply properties of operations as strategies.
- 1.OA.C.6: Add and subtract within 20.
- 1.NBT.B.2: Understand that the two digits of a two-digit number represent amounts of tens and ones.
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.