ZERO-IN

Italicized font represents information to be shared orally or physically completed with the students at this time.

The non-italicized font represents additional information included to support the teacher’s understanding of the content being introduced within the CELL.

ANALYZE IT

Instruct students to complete Table A in their SDRs then discuss it as a class. Use the suggested responses below to guide students’ answers.

Note: Questions marked with a triangle (∆) are included to enrich students’ understanding. These questions do not appear in students’ SDRs but should be used as additional discussion points during the PostLab.

• ∆ What caused a change in direction in the path of the planets or the Moon? The force of gravity caused a change in direction.

• ∆ What governs the movement of the planets around the Sun and the Moon around the Earth? Based on students’ models, students should indicate that the forward motion of the planets and the force of gravity between the Sun and the planets or the Earth and the Moon causes the planets to orbit the Sun, and the Moon to orbit the Earth.

• ∆ What would occur if the planets and the Moon did not experience forward motion? What would occur if the Sun and the Earth did not exert the force of gravity on the planets and on the Moon? Student answers will vary. Encourage students to answer and refrain from answering the question for them. Tell students that they will investigate these ideas in Investigation Four.

GET FOCUSED

Although the following Focus Question is not in students’ SDRs for Investigation 3, discuss it with students at this time. Use the suggested response below to guide students’ answers.

• What causes the orbit of the planets around the Sun and the Moon around the Earth? The combination of forward motion and gravity causes the planets to orbit the Sun and the Moon to orbit the Earth.

Note: The Focus Question for Investigation Three and Four is the same. Students continue to explore the orbit of the planets through both investigations.