Math Expressions Grade 3, Unit 5: Write Equations to Solve Word Problems
In this unit, your child writes equations, number sentences with an equal sign, to solve one-step and two-step word problems with all four operations, using a letter for the unknown. Children also look for patterns in addition and multiplication tables. It puts the last unit's adding and subtracting to work, and the next unit moves to shapes, perimeter, and area.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 5?
- Writing an equation with a letter for the unknown, like 4 x 6 + n = 30, to solve two-step word problems. Learn more: Story problems with two steps
- Finding patterns in addition and multiplication tables, such as odd plus odd always being even, and explaining why. Learn more: Spotting patterns in times tables
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
A bakery made 500 cookies. They sold 235 on Saturday and 190 on Sunday. How many are left?
- 75
- 85
- 175
How you can help
- Tell a two-step story at the store, such as '3 bags of 8 rolls, and we already have 5 at home. How many in all?' and ask your child to write an equation.
- Swap roles: ask your child to make up a two-step word problem for you to solve, then check together that your answer makes sense in the story.
- Add pairs of odd numbers on a walk, such as house numbers 13 and 17, and ask your child what kind of number comes out each time, and why.
Where kids can get stuck
- Doing the right operations in the wrong order, which tells a different story than the problem does.
- Stopping after one step, such as reporting the 24 rolls in the bags instead of the total with the 5 at home.
- Describing a pattern only by how the numbers look, saying 'it goes up by 5' without explaining why.
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
- equation
- A number sentence with an equal sign showing two sides are the same amount.
- unknown
- The missing number in a problem, shown by a box, a question mark, or a letter.
- variable
- A letter, like n, that stands for an unknown number.
- two-step problem
- A word problem that takes two calculations to solve.
- reasonable
- Making sense; close to what you would expect from an estimate.
- pattern
- Something that repeats or changes in a predictable way.
- even number
- A number that can be split into two equal groups, ending in 0, 2, 4, 6, or 8.
- odd number
- A number that cannot be split into two equal groups, ending in 1, 3, 5, 7, or 9.
Want to help your child master solving word problems?
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 Math Expressions Grade 3 Unit 5 cover?
Math Expressions Grade 3 Unit 5 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.