Bridges in Mathematics Grade 4, Unit 8: Playground Design & Measurement
In this unit, your child puts the year's math to work by designing a playground. They use the area and perimeter formulas to plan spaces, find a missing side when the area or perimeter is known, and solve multi-step problems along the way. It caps the review of fractions, decimals, and multiplication with a real, hands-on project.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 8?
- Solving multi-step planning problems, like costs and amounts of materials, and checking that each answer is reasonable. Learn more: Multi-step story problems and leftovers
- Using area = length × width and the perimeter formula to plan spaces, and finding a missing side from a known area or perimeter. Learn more: Using area and perimeter to solve real problems
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 class of 28 students splits into 4 equal teams for a game. Then 2 new students join one of the teams. How many students are on that team now?
- 9
- 7
- 30
How you can help
- Plan a pretend garden on paper. Give your child 20 feet of fence and ask how many different rectangles they can make, then which one has the most space inside.
- Measure a rug or table with a tape measure. Ask your child how much ribbon would go around the edge and how much space the top covers, and which number is which.
- Sketch a dream playground together. If a sandbox needs 48 square feet and is 6 feet wide, ask your child how long it must be, and how much border it needs.
Where kids can get stuck
- Multiplying the sides when the question asks for fence, answering 40 feet for an 8-by-5 space instead of 26.
- Adding only two sides for the perimeter, getting 13 feet for an 8-by-5 rectangle.
- Labeling an area in feet instead of square feet, or a perimeter in square units.
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
- area
- The space inside a flat shape, measured in square units.
- perimeter
- The distance all the way around a flat shape.
- formula
- A rule written with symbols, like area = length × width.
- square unit
- A square with sides 1 unit long, used to measure area.
- length
- How long something is from end to end.
- width
- How wide something is from side to side.
- multistep problem
- A word problem that needs more than one calculation to solve.
- reasonable
- Making sense; a reasonable answer is close to the estimate and fits the story.
Ready to build your child’s confidence with area and perimeter?
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 4 Unit 8 cover?
Bridges in Mathematics Grade 4 Unit 8 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.