Bridges in Mathematics Grade 1, Unit 2: Developing Ten & Teen Numbers
In this unit, first graders discover that every teen number is one ten and some ones, so 14 is a ten and 4 ones. They use that idea, and the fact that they can add in any order, to solve facts within 20. It builds on the counting and story problems from the last unit and sets up the next one, which adds, subtracts, counts, and compares bigger numbers.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 2?
- Solving story problems with teen numbers, using a ten and some ones to picture how many there are in each part. Learn more: Adding and subtracting story problems within 20
- Adding numbers in any order, starting with the bigger one or finding a ten first, because the total stays the same. Learn more: Adding in any order to make it easier
- Using ten as a stepping stone, so 9 + 5 becomes 10 + 4, to add and subtract within 20. Learn more about adding within 20: Adding within 20 · Learn more about subtracting within 20
- Seeing each teen number as one ten and some ones, so 17 is a ten and 7 ones. 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
- Bundle 10 straws or craft sticks with a hair tie, then add a few loose ones. Ask, "How many in all?" and let your child count on from 10 instead of starting at 1.
- Line up two rows of 5 spoons to make a ten, then add a few more beside them. Ask your child to name the number as a ten and some ones, like "a ten and 3 ones is 13."
- Ask turnaround questions on a walk or ride: "What's 3 + 8? And 8 + 3?" Talk about why starting with 8 and counting on 3 is quicker.
Where kids can get stuck
- Seeing 14 as just a number to count up to, rather than a ten and 4 more ones.
- Writing 41 for fourteen, because the word starts with the sound of four.
- Counting on from the smaller number, starting at 3 for 3 + 8 instead of starting at 8.
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.
- digit
- One of the symbols 0 to 9 used to write numbers.
- teen number
- A number from 11 to 19, made of one ten and some ones.
- turnaround fact
- The same addends in the other order, like 3 + 5 and 5 + 3.
- make a ten
- Split a number to fill a ten first, like 8 + 5 = 8 + 2 + 3.
- place value
- What a digit is worth because of its spot, like the 4 in 42 meaning 40.
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.
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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 Bridges in Mathematics Grade 1 Unit 2 cover?
Bridges in Mathematics Grade 1 Unit 2 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.