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Kindergarten · 1st Grade · K.G.B.4 · 1.G.A.1

Shape attributes in kindergarten and 1st grade

Shape attributes are the features that describe a shape, such as how many sides and corners it has. In kindergarten, your child compares shapes and says how they are alike and different. In 1st grade, your child learns which attributes decide a shape's name and which ones, like color or size, do not.

What the standards say

The official Common Core wording, quoted exactly. The plain version follows.

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 (e.g., number of sides and vertices/"corners") and other attributes (e.g., having sides of equal length).

1.G.A.1 Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size); build and draw shapes to possess defining attributes.

What it means, in plain words

Kindergarten: comparing shapes by their parts K.G.B.4

A side is a straight line on the edge of a shape. A corner is the point where two sides meet, and math books also call it a vertex. Counting the sides and corners of shapes is the main tool for comparing shapes in kindergarten. A triangle has 3 sides and 3 corners. A square has 4 of each. A circle has one curved edge and no corners.

Your child compares 2D shapes (flat shapes, like a square drawn on paper) and 3D shapes (solid shapes, like a box or a ball). Kindergarten uses everyday words for this. A box has flat sides and pointy corners. A ball is round all over and rolls. A can rolls on its side and stands on its flat end.

Shape attributes in kindergarten also include size and position. A big triangle and a small triangle are both triangles, and a triangle that points down is still a triangle. Seeing shapes in many sizes and turned many ways stops your child from judging a shape by how it usually sits in a picture book.

Your child should be able to:

  • Count the sides and corners of a flat shape
  • Say how two shapes are alike and how they are different
  • Notice when all the sides of a shape are the same length
  • Describe solid shapes with words like flat, round, rolls and stacks

Example

How are a square and a rectangle alike, and how are they different?

  1. Count the sides. The square has 4 sides and the rectangle has 4 sides.
  2. Count the corners. Each shape has 4 corners.
  3. Look at the side lengths. All 4 sides of the square are the same length. The rectangle has 2 long sides and 2 short sides.
  4. So both shapes have 4 sides and 4 corners, and only the square has 4 sides of the same length.

1st grade: the attributes that decide a shape's name 1.G.A.1

Shape attributes in 1st grade come in two kinds. A defining attribute is a feature that every shape with that name must have. A triangle must be closed, which means all its sides meet with no gaps, and it must have 3 straight sides. Teachers call these the defining attributes of shapes, because they decide the name.

A non-defining attribute can change without changing the name. Color, size and the way a shape is turned are non-defining. A tiny red triangle and a huge blue triangle that points down are both triangles.

Your child also builds and draws shapes that follow the rules: a square from 4 straws of the same length, or a rectangle with 4 square corners drawn on graph paper. A square corner is a corner like the corner of a sheet of paper.

Your child should be able to:

  • Name the defining attributes of a triangle, a square, a rectangle and a circle
  • Explain that color, size and turning do not change a shape's name
  • Tell why a shape with a gap or a curved side cannot be a triangle
  • Draw or build a shape that has the attributes asked for

Example

Draw three triangles that look different from each other. What do all three have in common?

  1. Draw one the usual way, sitting on its bottom side.
  2. Draw a long thin one. Then draw one standing on its point.
  3. Check each one: it is closed and it has 3 straight sides.
  4. All three are triangles. Their size and the way they are turned are different, and those features do not change the name.

Where children usually get stuck

  • Your child sees a square turned on its point and calls it a diamond, not a square.

    Most pictures show a square sitting on a flat side. The child learned the picture, not the rule of 4 equal sides and 4 square corners.

    What helps. Cut a square out of paper. Turn it slowly on the table and ask after each turn how many sides and corners it has now.

  • Your child counts the corners of a square and gets 3 or 5.

    With no starting point, the child loses track of which corners were already counted.

    What helps. Put a pencil mark on the first corner. Your child touches each corner once while counting and stops back at the mark.

  • Your child describes a shape by its color or size, like "the big one" or "the red one", instead of by its sides and corners.

    Color and size are the first things a young child notices, and the words are easy. Shape words take longer to feel useful.

    What helps. Play "I spy a shape" at home with one rule: the clue must say how many sides or corners, never the color.

Try four practice questions

Real kindergarten questions from our question bank, easiest first. Answer them right here, check each one, and see a worked solution for any question.

  1. 1Warm-up
    Look at the two shapes below.
    Which statement is true?
    A
    One shape has curved sides and one has straight sides.
    B
    Both shapes have curved sides.
    C
    Both shapes have 3 corners.
    D
    The shapes have the same number of corners.
    Show the answer and how to solve it

    The true statement is 'One shape has curved sides and one has straight sides.' The circle has curved sides and no corners. The triangle has 3 straight sides and 3 corners.

    1. 1Look at the first shape. It is a circle. The circle has curved sides going all the way around and no corners.
    2. 2Look at the second shape. It is a triangle. Count its sides and corners. The triangle has 3 straight sides and 3 corners.
    3. 3Now compare the two shapes. The circle has curved sides and the triangle has straight sides. So the true statement is 'One shape has curved sides and one has straight sides.'

    Common mistake. A common mistake is to say both shapes have curved sides. Look at the triangle closely — its sides are straight, not curved.

    The idea underneath. When you compare two shapes, count the sides and corners on each shape separately, and notice if the sides are straight or curved. Then check each statement to see if it really matches what you see.

  2. 2On level
    Here is a rectangle.
    None of the shapes below are rectangles. Sort each shape into the right group.
    Drag each item into the group where it belongs, or tap the item, then tap the group.
    Wrong number of sides
    Drag or tap items here
    Has a curved side
    Drag or tap items here

    Keyboard instructions: focus an item and press Enter or Space to pick it up. Move focus to a bin or the bank and press Enter or Space to drop it. Press Escape to cancel.

    Show the answer and how to solve it

    The green triangle and the orange shape with 5 sides go in 'Wrong number of sides' because they don't have 4 sides like a rectangle. The red circle goes in 'Has a curved side' because it is round.

    1. 1Look at the rectangle. It has 4 straight sides.
    2. 2Each shape below is not a rectangle. Look at each shape to see what is different.
    3. 3The green triangle has 3 straight sides. The orange shape has 5 straight sides. Neither has 4 sides, so both go in 'Wrong number of sides'.
    4. 4The red circle is round all the way. It has a curved side, so it goes in 'Has a curved side'.

    Common mistake. A common mistake is to put a round shape like the circle in 'Wrong number of sides' by trying to count where the curve bends. Round shapes don't have any straight sides — they belong in 'Has a curved side'.

    The idea underneath. A rectangle has 4 straight sides. If a shape has the wrong number of sides OR any curved side, it isn't a rectangle.

  3. 3On level
    Look at the shape. How many straight sides does it have?
    A
    4
    B
    3
    C
    2
    D
    6
    Show the answer and how to solve it

    The shape has 3 straight sides.

    1. 1Look at the shape. It is a flat shape with straight sides and corners.
    2. 2Pick a corner to start. Touch each side and count: 1, 2, 3. Stop when you get back to where you started.
    3. 3The shape has 3 straight sides.

    Common mistake. A common mistake is skipping a side (counting 2) or counting the first side twice (counting 4). To avoid this, pick a corner to start, touch each side once as you count, and stop right before reaching your starting corner again.

    The idea underneath. Each side of a flat shape is one straight line between two corners. You count once for each straight line, no matter how big or small the shape is, and no matter how the shape is turned.

  4. 4Stretch
    Liam looks at these triangles.
    Liam says, "Triangles have all sides the same length."
    Pick the best answer.
    A
    No. Triangles can have different side lengths.
    B
    Yes. Every triangle has equal sides.
    C
    No. Triangles never have equal sides.
    D
    Yes. Equal sides make a triangle.
    Show the answer and how to solve it

    The right answer is "No. Triangles can have different side lengths." A triangle is still a triangle even when its sides are not all equal — having 3 sides and 3 corners is what makes it a triangle.

    1. 1Look at the three triangles in the picture. The blue one is tall and narrow, the orange one is wide and flat, and the teal one is in between. They have different sizes and proportions, but they are all triangles.
    2. 2Liam says triangles have all sides the same length. But the picture shows that is not right — the wide orange triangle has sides that look very different from each other. So Liam's rule is wrong.
    3. 3The correct answer says triangles can have different side lengths. A triangle is still a triangle no matter how long its sides are, as long as it has 3 sides and 3 corners.

    Common mistake. A common mistake is to agree with Liam because many familiar triangles look like they have equal sides. Always check the picture — the wide orange triangle shows that sides can look very different from each other.

    The idea underneath. What makes a triangle a triangle is having 3 sides and 3 corners — not how long the sides are.