McGraw Hill
Glencoe Mathematics: Online Study Tools: Line and Angle Relationships
This site gives a short interactive quiz which allows students to self-assess their understanding of the concept of line and angle relationships.
Science Education Resource Center at Carleton College
Serc: Westward Ho! How Far Is Yonder Mountain
In this lesson quantitative skills in geologic context are reinforced. Young scholars create a spreadsheet to calculate the distance of a peak using vertical angles sighted from a wagon train heading directly for the peak. The...
Illustrative Mathematics
Illustrative Mathematics: G Gpe.5 Triangles Inscribed in Circle
In this task, students use ideas about linear functions to determine when certain angles are right angles. They use the fact that two lines (if not vertical or horizontal) are perpendicular when their slopes are inverse reciprocals, as...