Mathematics·Geometry·conceptual
Angles with parallel lines
Understand and use the relationship between parallel lines cut by a transversal: corresponding angles, alternate interior angles, and co-interior (same-side interior) angles; use these to find unknown angles
Suggested ages 12–14
Evidence of understanding
- Identify alternate, corresponding, and co-interior angle pairs in a diagram with parallel lines
- Explain why alternate angles are equal using the concept of translation along the transversal
- Find missing angles in a parallel-line diagram using a combination of angle relationships
Assessment prompt
If Angles with parallel lines sees a Z-shape or F-shape formed by two parallel lines and a crossing line in a diagram, can they identify the equal angles and explain why they’re equal?
Standards alignment
8.G.5US · ccss-math
Angle arguments and similarity
Common Core State Standards for Mathematics · 8
KS3.Maths.Geo.11GB · uk-nc-2013
Parallel Lines and Angles
The national curriculum in England: Key stages 1 and 2 framework document · Key Stage 3