Zearn Math Grade 2, Mission 4: Addition and Subtraction Within 200 with Word Problems to 100
In this unit, your child adds and subtracts within 200, using what they know about tens and hundreds. They use mental math, drawings, and written steps; regroup when needed; add or subtract 10 and 100 in their heads; and solve story problems within 100. It builds on place value to 1,000 and leads into addition and subtraction within 1,000.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Mission 4?
- Solving one- and two-step story problems within 100, drawing tape diagrams to see which parts are known and which is missing. Learn more: One- and two-step story problems within 100
- Adding and subtracting within 100 with written steps, such as 56 + 37, regrouping 13 ones as 1 ten and 3 ones. Learn more about adding within 100: Adding within 100 · Learn more about subtracting within 100
- Adding and subtracting within 200, like 145 + 38 or 172 - 56, using place value drawings and written steps. Learn more about adding within 1,000: Adding within 1,000 · Learn more about subtracting within 1,000
- Adding or subtracting 10 and 100 mentally, like knowing 10 more than 145 is 155. Learn more: Adding or taking away 10 or 100 mentally
- Explaining why a written method works by matching each step to a place value drawing. Learn more about explaining why addition strategies work: Explaining why addition strategies work · Learn more about explaining why subtraction strategies work
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
What is 80 minus 20?
- 50
- 60
- 70
How you can help
- Keep a running score in a game and let your child add each round, like 145 + 38. Ask them to say what they do with the extra ones.
- Ask '10 more?' and '100 less?' on a walk or ride with numbers like 145 or 172. Switch roles so your child gets to quiz you.
- Tell a two-step story at the store: 'We need 50 napkins. We have 18, then find 12 more. How many more do we need?'
Where kids can get stuck
- Writing all of 13 in the ones place when adding 56 + 37, instead of regrouping it.
- Stopping after one step of a two-step story and giving the in-between amount as the answer.
- Drawing a model that does not match, such as 6 tens and 3 ones for 36.
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
- regroup
- To trade 10 ones for 1 ten, or 10 tens for 1 hundred, and back again.
- sum
- The answer when you add. In 8 + 5 = 13, the sum is 13.
- difference
- The answer when you subtract. In 13 - 5 = 8, the difference is 8.
- tape diagram
- A drawing of long bars, like strips of tape, that shows the parts of a story problem.
- mentally
- In your head, without writing it down.
- place value
- What a digit is worth because of where it sits. In 352, the 5 means 50.
- two-step problem
- A story problem that needs two math steps to solve.
Ready to build your child’s confidence with adding and subtracting to 200?
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 2 Mission 4 cover?
Zearn Math Grade 2 Mission 4 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.