Investigating Rotation: Why Is There Day and Night?

This lesson is designed for students to participate in an activity that will allow them to see how the earth's rotation and the sun cause day and night. Students will think critically while observing, developing questions, and investigating. They will also review the vocabulary words "rotation", "day", and "night".

This lesson is designed for grade 3, but could be used for others with some adjustment. It is designed to be part of a solar system unit. Prior to the activity, students should understand that the earth is a sphere that is tilted on an axis. They should also be able to determine where their state would be located on the globe. To determine prior knowledge of rotation and to encourage questioning, a KWL chart can be used before starting this activity. The materials needed for this activity include: baseball-sized Styrofoam balls, flashlights, knitting needles or thin wooden dowels, and pins.

Use a Styrofoam ball as a model of the earth, push a knitting needle or thin wooden dowel through it to create an axis, and place a pin where Minnesota would be. Have the students discuss how the ball is like the earth. Darken the room and shine a flashlight on the ball to represent the sun. Ask the students what the flashlight represents. Then have them observe the display and write down what they notice in their science notebooks. While they are doing so, slowly rotate the ball counterclockwise to imitate the earth's rotation. In small groups, have students discuss what they noticed and come up with 2 or 3 questions they have about what they saw. After writing the questions and posting them, hand out student materials and allow the groups time to create and manipulate the display. Were they able to recreate the demonstration? As a class, discuss their findings and decide which of their questions have been answered. Also discuss: Which side of the globe is having day and which is having night? Why does the sun shine on different parts of the earth at different times? What would happen if the earth didn't turn?The main focus for class discussion should be the earth's complete rotation from west to east every 24 hours to cause day and night. Also, that the sun is always shining, just not on the same place on the earth.

This lesson was created to be used in a unit following the book, The Magic School Bus Lost in the Solar System by Joanna Cole and Bruce Degen. I have not used this lesson before, and will be working with my students beforehand to develop observation and questioning skills.

Assessment is done by observation during the activity and by reading the students' observations from the lesson. Students will also complete a diagram explaining how the relationship between the earth and sun causes day and night.

3.I.B.1: asking questions3.III.C.1: rotation