3rd Grade Geometry Practice: 20 Multiple-Choice Questions on Shapes, Measurement & 2D Properties

By 3rd grade, math starts to feel a lot bigger — and geometry is one of the biggest jumps. Your child moves from just recognizing shapes ("that's a circle, that's a triangle") to reasoning about shapes: how many sides, how many right angles, whether opposite sides are parallel, how much space a shape covers, and how long the boundary around it is.

This practice set is 20 medium-level multiple-choice questions on the geometry and measurement topics your child is expected to master in Common Core Grade 3: identifying and classifying 2D shapes, finding perimeter and area of rectangles, recognizing right angles and lines of symmetry, and choosing appropriate units of measurement. Every question has 4 choices, and the answers are hidden until you press the button at the bottom.

What 3rd graders learn in geometry & measurement

The Common Core Grade 3 standards break geometry and measurement into three big ideas:

1. 2D shapes and their properties. Third graders learn that shapes belong to categories based on their attributes — the number of sides, the number of vertices (corners), whether the sides are parallel or equal, and whether the angles are right, acute, or obtuse. This is where kids start to see that a square is a special rectangle, a rectangle is a special parallelogram, and a parallelogram is a special quadrilateral. Being able to say why a shape belongs to a category is a huge cognitive leap from earlier grades.

2. Area and perimeter. This is the flagship topic of 3rd grade geometry. Students learn to tile a rectangle with unit squares to find its area, connect that tiling to multiplication (length × width), and separately measure the boundary of a shape to find its perimeter. Keeping these two concepts distinct — area is "how much space fits inside," perimeter is "how far around the edge" — is a real challenge for 8- and 9-year-olds and one of the most common places we see confusion.

3. Measurement. Third graders measure lengths in inches, centimeters, and meters; they learn to pick the right unit for the right object (you'd measure a pencil in centimeters, not kilometers); and they start estimating — a hugely important habit because it teaches kids to check whether an answer makes sense in the real world.

Layered on top of all of this are foundational ideas that keep showing up later: right angles (the corners of a square), lines of symmetry (fold the shape and both halves match), and partitioning shapes into equal parts — which is really the geometric side of fractions.

How SOMATH helps 3rd graders build these skills

At School of Math (SOMATH) on the Upper West Side, our 3rd graders sit in our Kid Einsteins class — a small group of six students, taught in person by the same teacher every week. Geometry isn't a rushed unit at the end of the year; it's woven through the whole curriculum so kids can see how shapes, measurement, and multiplication connect.

In a typical Kid Einsteins geometry lesson, students actually build the shapes they're studying. We use pattern blocks, geoboards, rulers, and grid paper — not just worksheets — to make ideas like area and perimeter physical before they become abstract. When we teach the area of a rectangle, kids literally tile it with square tiles first, count the tiles, and then discover on their own that "hey, that's the same as multiplying the sides." That moment of discovery sticks in a way that memorizing a formula never does.

Each 2-hour class follows the same structure: a warm-up review, a new concept with worked examples, small-group guided practice, a real-world word problem, and a mini-quiz at the end that goes home with corrections. Because our courses are rolling, your child can join at any class and continue into the next term without losing the thread.

20 practice questions (medium level)

Have your child work through all 20 questions before pressing the answer button at the bottom. Pencil, paper, and a ruler help.

Medium · 20 Questions

How to coach a 3rd grader through these

Four habits from our Upper West Side classroom:

1. Draw the shape every time. Even if the problem gives numbers, ask your child to sketch the rectangle before doing any arithmetic. Drawing makes "6 × 4" concrete — a rectangle with 6 rows of 4 boxes — and prevents the area-vs.-perimeter mix-up.
2. Count sides and corners out loud. When naming a 2D shape, always count. "One, two, three, four, five, six sides … six corners … hexagon." This habit reinforces the defining attributes that Grade 3 asks about.
3. Ask "does that answer make sense?" every time. If the question is about the perimeter of a piece of paper and your child says "8 centimeters," gently ask: is that a real-world answer? Grade 3 introduces estimation for exactly this reason.
4. Use a ruler for real things at home. Measure the kitchen table, a book, a shoe. Practice picking units: "Would we measure our couch in centimeters or in meters?" Ten minutes at the dinner table is worth more than a whole workbook page.