Mathematics K–6 · Kindergarten
Feel and name: sorting 2D shapes by their features
Measurement and space
The idea
A shape is named by its features, such as how many straight sides and corners it has, and not by which way up it is.
Safety card
Hazards
- sharp corners on thin plastic shapes
Controls
- use thick card or rounded plastic shapes
Note
No chemicals or heat are used, so the NSW Department of Education Chemical Safety in Schools package is not needed; ordinary classroom supervision under the school's usual risk management.
What you need
- 12 thick card or plastic shapes: 3 triangles, 3 squares, 3 rectangles and 3 circles, in different sizes
- a cloth bag
- 4 sorting hoops or sheets of paper labelled 0 sides, 3 sides, 4 sides equal, 4 sides two long two short
How to do it
- Without looking, the child puts a hand in the bag, feels one shape and describes it: straight or curved edges, how many corners.
- The child names the shape before pulling it out, then checks by looking.
- Sort all 12 shapes into the hoops by counting straight sides and corners. Count the shapes in each hoop.
- Turn a triangle so that a point faces down, and a square so that a corner faces down. Ask whether the shape has changed. Count the sides again.
- Walk around the room and find one object that shows each shape (a window, a clock face, a roof on a picture).
What you should see
The hoops hold 3 circles (0 straight sides, 0 corners), 3 triangles (3 sides, 3 corners), 3 squares and 3 rectangles (4 sides, 4 corners each). Children who separate squares from rectangles do so by checking that all four sides of a square are the same length. A triangle turned point-down still has 3 sides and 3 corners and stays in the triangle hoop.
What changes
This activity lists no variables to change, measure and keep the same.
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- A triangle with its point facing down is not a triangle.
- A square turned onto a corner is a different shape called a diamond.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Mathematics K-10 Syllabus (2022), NSW Education Standards AuthorityMAE-2DS-01MAO-WM-01
- Australian Curriculum v9AC9MFSP01
Sources
The pages the author read to write this activity.