Classifying shapes by line properties
Classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or angles of a specified size; recognise right triangles as a category
What a learner can do afterwards
- Sort a set of quadrilaterals into those with parallel sides and those without
- Identify which triangles in a set are right triangles
- Classify shapes that have both perpendicular and parallel sides
The lesson
You already know what parallel and perpendicular lines look like. Now you can use those same clues to sort shapes into groups: shapes with parallel sides, shapes with perpendicular sides, and shapes with both.
Omar looks at a triangle and finds one corner that makes a perfect square, like the corner of a book page. That square corner is a right angle, so Omar calls it a right triangle.
To sort shapes fast, look for two clues: arrows on sides mean they are parallel, and a small square in a corner means a right angle. Some shapes show both clues at once.
Sort shapes by their lines: look for parallel sides and right angle corners, and remember a right triangle has just one right angle.
Watch it
Where it sits
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.