What is sorting?
To sort means to put things into groups that are alike. To classify means to decide which group each thing belongs in. When you put away toys, socks or crayons, you’re sorting!
Sorting by attribute
An attribute is a feature you can notice:
| Attribute | Groups you could make |
|---|---|
| Colour | red, blue, yellow |
| Shape | circles, squares, triangles |
| Size | big, small |
| Use | things to eat, things to wear |
| Number | 2 legs, 4 legs, no legs |
The sorting rule
The rule tells why things are in the same group. "These are all red." "These all have 4 legs." Every object must follow the rule of the group it’s in.
A fun game: someone sorts objects without saying the rule, and others try to guess it.
One collection, many ways
The same buttons can be sorted in different ways:
- By colour: red buttons, blue buttons.
- By holes: 2 holes, 4 holes.
- By size: big, small.
There is often more than one right answer, as long as you can say your rule.
Things that fit two groups
What if something fits both groups? A red square is red and a square. A Venn diagram uses two overlapping circles. Things that fit both rules go in the middle where the circles overlap. Things that fit neither go outside the circles.
| Only red | Red and square (overlap) | Only square |
|---|---|---|
| red circle | red square | blue square |
Yes / no sorting
A simple way to sort is with a yes/no question: "Does it have wheels?" Then make a YES group and a NO group.
Worked examples
Example 1: Sort these into two groups: apple, car, banana, bus, grape, bike.
Rule: food vs. vehicles. Food: apple, banana, grape. Vehicles: car, bus, bike.
Example 2: What is the rule? Group A: cat, dog, horse. Group B: chicken, duck, owl.
4 legs vs 2 legs (or animals vs birds).
Example 3: Where does a blue triangle go in a Venn diagram of "blue" and "triangles"?
In the middle, because it is both.
Common mistakes
- Changing the rule partway through sorting.
- Putting an object in a group whose rule it doesn’t follow.
- Forgetting the overlap when something belongs in two groups.
Try it yourself
- Sort these by colour: red ball, blue car, red hat, blue sock.
- What rule could sort: spoon, fork, sock, shoe?
- Where does a yellow circle go in a Venn diagram of "red" and "squares"?
- Name two ways to sort crayons.
Answers: 1) Red: ball, hat. Blue: car, sock. 2) things for eating vs things to wear 3) outside both circles 4) e.g. by colour, by length
Quick recap
- Sort and classify things into groups by an attribute.
- Each group has a rule.
- A Venn diagram shows things that fit more than one group.