Zearn Math Grade 1, Mission 6: Place Value, Comparison, Addition and Subtraction to 100
In this unit, your child stretches place value to 100 and beyond, counting to 120 and adding and subtracting with tens and ones. They compare two-digit numbers, find 10 more and 10 less, and make new tens when adding. This final unit builds on the numbers to 40 and geometry units and sets up second grade.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Mission 6?
- Counting, reading, and writing numbers all the way to 120, especially across 100, like 99, 100, 101. Learn more: Counting, reading, and writing numbers to 120
- Using tens and ones to show any number to 100, like 76 as 7 tens and 6 ones. Learn more: Tens and ones in two-digit numbers
- Comparing numbers to 100 by looking at the tens, then ones, and writing the result with >, <, or =. Learn more: Comparing two-digit numbers with >, =, and <
- Adding two-digit numbers within 100, like 58 + 7 or 34 + 40, and making a new ten when needed. Learn more: Adding two-digit numbers within 100
- Finding, in their head, 10 more and 10 less than numbers up to 100, such as 86 becoming 96 or 76. Learn more: 10 more or 10 less in your head
- Subtracting tens from tens within 100, like 90 - 50, with models and drawings. 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 steps on a long walk, keeping a running total, and keep going past 100. Ask your child to write the final number when you stop.
- Make up quick adding questions at dinner, like "58 + 7," and ask your child to explain how they used tens and ones.
- Play 10 more and 10 less while waiting in line. Say 86, and have your child answer 96 and 76.
Where kids can get stuck
- Writing 58 + 7 as 515, putting all 15 ones beside the 5 tens.
- Saying 10 more than 92 is 93, changing the ones digit instead of the tens.
- Reading 102 as twelve, skipping the zero in the tens place.
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.
- place value
- What a digit is worth because of where it sits, like the 5 in 52 meaning 50.
- digit
- One of the symbols 0 to 9 used to write numbers.
- new ten
- Ten ones grouped together to make one ten when adding.
- 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.
- hundred
- Ten groups of ten, written 100.
Ready to build your child’s confidence with place value 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 Zearn Math Grade 1 Mission 6 cover?
Zearn Math Grade 1 Mission 6 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 1.NBT.A.1: Count to 120, starting at any number.
- 1.NBT.B.2: Understand that the two digits of a two-digit number represent amounts of tens and ones.
- 1.NBT.B.3: Compare two two-digit numbers.
- 1.NBT.C.4: Add within 100.
- 1.NBT.C.5: Given a two-digit number, mentally find 10 more or 10 less.
- 1.NBT.C.6: Subtract multiples of 10 in the range 10-90.
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.