Golfball Phases and Embroidery Hoop Eclipses
Type and level of course in which you would use this activity:
We've used this activity with teachers, pre-service teachers, and with middle school students. However, at the undergraduate level, it could be done in a small lab, or modified for a large lecture class with the use of a video camera capturing and projecting the user's point of view.
Skills and concepts that students should have mastered before beginning the activity:
The names of the phases of the Moon and their order, the relative size and distance of the Moon, the tilt of the Moon's orbit with respect to the ecliptic, and the Sun's role as the source of light.
How the activity is situated in its course
This is conducted within a sequence of activities. We start with activities observing the Moon's phases, we model the Earth-Moon size and distance, we discuss the Moon's orbit (length, the plane of the orbit, the shape), before conducting this activity. After, we assess with a kinesthetic activity using paper plates.
In the first half, students explore the dynamics of lunar phases to develop an understanding of the relative positions of our Moon, Earth, and Sun that cause the phases of the Moon as viewed from Earth. Using a golf ball glowing under the ultraviolet light of a “blacklight” makes it easier to see the actual phase of the Moon.
In the second half, students kinesthetically model the orbit of the moon relative to the Earth's revolution around the Sun to gain a deeper understanding of eclipses.
We hand out paper plates with different lunar phases drawn on them, position a beachball Sun and an Earth globe and ask the students to move to the correct position for their phase relative to the Earth and Sun (and each other). For eclipses, we invite the students to describe how often eclipses can occur each year.