May 11, 2015

Teacher and Student versions of full lesson from engageNY

Students develop the definition of circle using diameter and radius.

Students know that the distance around a circle is called the circumference and discover that the ratio of the circumference to the diameter of a circle is a special number called pi, written ?.

Students know the formula for the circumference C of a circle of diameter d and radius r. They use scale models to derive these formulas.

Students use 22/7 and 3.14 as estimates for ? and informally show that ? is slightly greater than 3.

- Mathematics > General
- Mathematics > Geometry

- Grade 9
- Grade 10

Reason abstractly and quantitatively.

Use appropriate tools strategically.

Attend to precision.

Look for and make use of structure.

Know 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.