Making Angles on a Circle

Learning Resource Type

Learning Activity

Subject Area

Mathematics

Grade(s)

Overview

Students will divide a clock into equal parts to form angles. Students will use the clock hands as rays to form angles.

This activity results from the ALEX Resource Gap Project.

Phase

During/Explore/Explain

Mathematics (2019) Grade(s): 4

MA19.4.24
Identify an angle as a geometric shape formed wherever two rays share a common endpoint.

Vocabulary

Angle
Ray
Endpoint
Geometric shape
Vertex
Line
Point
Line segment

Knowledge

Students know:

Angles are geometric shapes formed when two rays share a common endpoint.
How to draw points, lines, line segments, and rays

Skills

Students are able to:

Identify an angle as two rays with a common endpoint.

Understanding

Students understand that:

angles are geometric shapes made of two rays that are infinite in length and are measured with reference to a circle with its center at the common endpoint of the rays.

Learning Objectives

I can form an angle using two rays that share a common endpoint.

I can divide a circle into equal parts to form angles.

Activity Details

Display the clock with no hands on an interactive whiteboard or pass out paper copies of this clock. Review with the students that the measurement of a circle is 360°. Explain to the students that they will draw the hands (rays) of the clock to form angles. Use the following questions to lead a class discussion allowing the students time to draw each angle.

If we divided the clock (circle) into halves, what would be the measurement of each half? Allow one student to come to the board and draw an example of this angle. Students should discover that 6:00 makes a straight angle of 180°.

If we divided the clock into four equal quarters, what would be the measurement of each quarter? Allow one student to come to the board and draw an example of this angle. Students should discover that dividing the circle into fourths creates right angles of 90°. You can further discuss the 180° and the 270° angle if desired.

If we divided the clock into three equal sections, what would be the measurement of each section? Allow one student to come to the board and draw an example of this angle. Students should discover that this creates obtuse angles of 120°.

If we divided the clock into eight equal sections, what would be the measurement of each section? Allow one student to come to the board and draw an example of this angle. Students should discover that this creates acute angles of 45°.

Assessment Strategies

The students will complete the following exit pass:

If it is 9:00 p.m. on the clock, what angle do the hour and minute hands make?

If it is 6:00 a.m. on the clock, what angle do the hour and minute hands make?

The students should identify that the 9:00 p.m. angle forms a right angle of 90° but they might identify that angle as 270° if you discussed that in the class discussion.

Background / Preparation

The teacher will need to be able to display the clock with no hands on a whiteboard where the students can draw and erase easily. If there is not access to an interactive whiteboard, the students can use paper copies.

https://jacobsmedia.com/wp-content/uploads/2018/06/clock-with-no-hands-yellow.p…

Approved Date

2018-06-26

Owner (Author)

scarver17

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