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Comparing Shapes by Their Parts

A 30-minute Kindergarten lesson on describing how two shapes are alike and different by counting their sides and corners rather than by how they look.

Comparing Shapes by Their Parts is a free 30-minute Kindergarten maths lesson plan for Common Core standard K.G.B.4 — compare shapes and describe how they are alike and different. It is timed across 5 sections, gives the exact wording to use where the wording carries the mathematics, names 3 misconceptions with the teaching move that addresses each, and ends with an exit ticket and a printable worksheet with its answer key.

Grade:
Kindergarten
Length:
30 minutes
Standard:
K.G.B.4

Kindergarten · Geometry

K.G.B.4

Analyze and compare two- and three-dimensional shapes, in different sizes and orientations, using informal language to describe their similarities, differences, parts, and other attributes.

Objective

Students will be able to compare two shapes by their sides, corners and faces, and say one way they are alike and one way they differ.

Students are successful when they can

  • Counts sides and corners accurately on a flat shape.
  • Names one similarity and one difference between two shapes.
  • Groups shapes that share a feature even when they look different.

What you need

  • Shape tiles including hexagons and irregular quadrilaterals
  • Solid shapes for comparison
  • Sorting hoops
  • The printable practice sheet linked at the end of this plan

The lesson

Warm-up — count round

4 min
  1. Hold up shapes one at a time. Class counts the sides aloud, then the corners.
  2. Include a hexagon, where the count is genuinely worth doing rather than recognised instantly.

Teach — same and different, said precisely

9 min
  1. Put a square and a long rectangle side by side. Ask how they are the same.
  2. Push past 'they both have straight sides' to the count: four sides and four corners each.
  3. Now ask how they differ. All four sides equal on one, two long and two short on the other.
  4. Repeat with a triangle and a square, where the counts differ and the similarity has to be found elsewhere — both have straight sides, both are flat.
  5. Finish with a circle and a sphere: one flat, one solid, both with no corners at all.
“Alike and different are both answers. Counting the sides gives you one; looking at the lengths gives you the other.”

Guided practice — the odd one out

8 min
  1. Give each pair three shapes and ask which is the odd one out, and why.
  2. Insist there is more than one right answer, and ask for a second one.
  3. The second answer is where the thinking happens — the first is usually the obvious visual difference.

Independent practice

6 min
  1. Children complete a compare-shapes page.
  2. Answers based on colour or size mean the attributes that define a shape have not separated from the ones that do not.

Close

3 min
  1. Show a square and a triangle. Ask for one way they are the same.
  2. Collect three different correct answers and stop there.

What goes wrong, and why

Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.

Says two shapes are different because one is red and one is blue.

Why: Colour is the most visible difference and nothing has yet said which differences count in mathematics.

Fix: Give two identical shapes in different colours and ask if they are the same shape. The answer forces colour out of the list without a rule being announced.

Counts the corners of a hexagon as five or seven.

Why: There is no starting mark, so the count either misses the first corner or repeats it. This is the circle-counting problem in a new place.

Fix: Mark the starting corner with a finger or a dot. The rule is the same one used for counting objects in a circle, and naming that connection helps.

Says a big square and a small square are different shapes.

Why: Size is still part of identity, the same way orientation was.

Fix: Count sides and corners on both. Four and four either way, and the counts are the definition. Put them one on top of the other to show the shape is the same.

If they are not there yet

  • Compare two shapes at a time rather than three, and start with a pair that differ in side count so the comparison is clear.
  • Let the child trace round the shape with a finger while counting, so each side is touched once.

If they finish early

  • Find two shapes with the same number of sides but different side lengths.
  • Compare a cube and a square, and work out how many squares would be needed to cover the cube.
  • Sort a mixed set by number of corners and describe each group.

Exit ticket

How is a square like a rectangle? How is it different?

What to look for: Four sides and four corners on both, and equal sides on the square only. An answer about colour or size means the defining features have not separated from the decorative ones yet.

Printable practice for K.G.B.4

Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.

Questions about Comparing Shapes by Their Parts

How long does the Comparing Shapes by Their Parts lesson take?

30 minutes, split across 5 timed sections: warm-up 4 min, teach 9 min, guided practice 8 min, independent practice 6 min, close 3 min. The minutes are stated per section and add up to the stated length, so the plan can be cut or extended at a section boundary rather than abandoned halfway.

Which standard does Comparing Shapes by Their Parts teach?

CCSS.MATH.CONTENT.K.G.B.4 — K.G.B.4, Geometry for Kindergarten: “Analyze and compare two- and three-dimensional shapes, in different sizes and orientations, using informal language to describe their similarities, differences, parts, and other attributes.” In plain terms, compare shapes and describe how they are alike and different.

What do I need to teach this lesson?

Shape tiles including hexagons and irregular quadrilaterals, solid shapes for comparison, sorting hoops and the printable practice sheet linked at the end of this plan. Everything listed is either ordinary classroom equipment or a free printable from this site — there is nothing to buy and nothing to prepare beyond photocopying.

What mistakes should I expect in this lesson?

Three, each a reasoning error rather than carelessness: says two shapes are different because one is red and one is blue; counts the corners of a hexagon as five or seven and says a big square and a small square are different shapes. The plan gives the thinking behind each one and the teaching move that addresses the thinking rather than the symptom.

How do I know whether the lesson worked?

The exit ticket asks: “How is a square like a rectangle? How is it different?.” Four sides and four corners on both, and equal sides on the square only. An answer about colour or size means the defining features have not separated from the decorative ones yet. That tells you whether the class needs a reteach or a thirty-second conversation before you plan tomorrow.

Is there a worksheet to go with Comparing Shapes by Their Parts?

Yes — 2 printable K.G.B.4 worksheets, linked at the end of the plan and free like the rest of the site. Each one comes with an answer key and 25 versions, so the practice after the lesson can be a different paper on every desk.

Is Comparing Shapes by Their Parts free to use?

Yes. The plan, its printables and their answer keys are free to read, print and photocopy for your own class, with no account and no email capture. It was last reviewed on 5 September 2026. Please do not resell it or republish it as your own.

Last reviewed 2026-09-05. Aligned to K.G.B.4 of the Common Core State Standards for mathematics.