Bridges in Mathematics Grade 3, Unit 6: Geometry
In this unit, your child sorts shapes by their attributes, the features you can check, like the number of sides or square corners. They learn that squares, rectangles, and rhombuses all belong to the quadrilateral family, split shapes into equal parts, and measure perimeter. Fractions and bigger multiplication come next, so the equal-parts work here gives them a head start.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 6?
- Sorting four-sided shapes into families, such as seeing that a square is also a rectangle and a rhombus. Learn more: Sorting four-sided shapes into families
- Splitting a shape into equal parts and naming one part as a unit fraction, like 1/6 of a hexagon. Learn more: Splitting shapes into equal parts
- Finding perimeter, the distance all the way around a shape, by adding every side length. Learn more: Perimeter: the distance around a shape
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
Look at the shapes. They are all quadrilaterals. How many of them have 4 square corners?
- 2
- 3
- 1
How you can help
- Look for four-sided shapes on a walk, such as windows, signs, and doors, and ask your child which family each belongs to and how they know.
- Fold a square napkin into 4 equal parts two ways, strips and smaller squares, and ask whether each part is still 1/4 and why.
- Wrap a piece of string around a placemat or book, then straighten it and measure it with a ruler to find the perimeter.
Where kids can get stuck
- Saying a square is not a rectangle because it does not look long and thin.
- Calling a tilted square a diamond, thinking a turned shape becomes a different shape.
- Adding only the two side lengths shown, so a 5 by 3 rectangle gets a perimeter of 8 instead of 16.
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
- quadrilateral
- A flat shape with exactly 4 straight sides and 4 corners.
- rhombus
- A quadrilateral whose 4 sides are all the same length.
- rectangle
- A quadrilateral with 4 square corners.
- attribute
- Something about a shape you can check, like how many sides it has.
- perimeter
- The distance all the way around the outside of a shape.
- unit fraction
- A fraction with 1 on top, like 1/4, that names one equal part.
- equal parts
- Parts that are all exactly the same size.
Want to help your child master shapes 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.
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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 Bridges in Mathematics Grade 3 Unit 6 cover?
Bridges in Mathematics Grade 3 Unit 6 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.