Bridges in Mathematics Grade 1, Unit 7: One Hundred & Beyond
In this unit, first graders count, read, and write numbers to 120 and use tens and ones to add and subtract bigger numbers. They find 10 more or 10 less in their heads, which changes only the tens digit, the digit on the left. Their quick facts from the last unit make this work smoother, and next they use these numbers to sort data, tell stories, and look at change.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 7?
- Counting by ones and tens past 100 to 120, and writing numbers like 105 and 117 correctly. Learn more: Counting, reading, and writing numbers to 120
- Adding numbers within 100, like 36 + 7 or 45 + 30, by putting tens with tens and ones with ones. Learn more: Adding two-digit numbers within 100
- Finding 10 more or 10 less than a number in their heads and explaining why only the tens digit changes. Learn more: 10 more or 10 less in your head
- Subtracting tens from tens, like 90 - 40, by thinking of it as 9 tens take away 4 tens. 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
Count by tens: 10, 20, 30, 40, __. What number comes next?
- 51
- 50
- 60
How you can help
- Count by tens together while walking or riding, starting from an odd spot like 7: 17, 27, 37, all the way to 117. Then count back down by tens.
- Ask at the store what 10 more or 10 less than a price would be, like 10 more than 46 cents. Ask which digit changed and which stayed the same.
- Make bundles of ten with straws or craft sticks, plus a few loose ones, to show 36 + 7. Ask your child to make a new ten from the loose ones when there are enough.
Where kids can get stuck
- Writing one hundred five as 1005, putting 100 and 5 side by side.
- Saying 10 more than 46 is 47, changing the ones digit instead of the tens digit.
- Writing 4 instead of 40 for 70 - 30, forgetting the answer is in tens.
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
- hundred
- Ten tens, written 100.
- 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.
- tens digit
- The digit on the left in a two-digit number; it tells how many tens.
- 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.
- sum
- The answer when you add, like 7 in 3 + 4 = 7.
- multiple of 10
- A number you say when counting by tens, like 30 or 70.
Want to help your child master numbers to 120?
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 Bridges in Mathematics Grade 1 Unit 7 cover?
Bridges in Mathematics Grade 1 Unit 7 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.