GeometryCirclesabout 3 minCCSS HSG.C.A.2Identify and describe relationships among inscribed angles, radii, and chords. Include the relationship between central, inscribed, and circumscribed angles; inscribed angles on a diameter are right angles; the radius of a circle is perpendicular to the tangent where the radius intersects the circle.CCSS HSG.CO.A.1Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc.+0
Swing a ball on a string, let go, and land it in the pool.
Lesson Plan
Explore tangent lines to a circle, and see why a tangent is perpendicular to the radius where it touches.
Question: Ask what students spot and what they are curious about. Read “Which way does the ball fly?” aloud. Have each student guess and say why.
Question: Read “When do you let go?” aloud. Have partners explain their guesses to each other.
Big idea: Pause. Ask a student to say the idea in their own words.
Your turn: Have students try their own. Ask them to predict before they test.
How to run it
Whole classPut the lesson on the board. At each choice the class votes, then you select the winner.
SoloShare the link, QR code, or post to Google Classroom. Each student gets to take their own path.
