As you become more familiar with the NGSS, you’ll find patterns in performance expectations across grade bands. One of those patterns is they way in which students engage in understanding and describing the Sun-Moon-Earth system.  Connecting those big ideas to a phenomena students observe and describe is one way to both elicit student current understanding (or misconceptions)  and to provide a context in which they can observe, argue or develop a model of the phenomena.

The question, “How big is the moon?” can help us understand how students think about scale.   We can extend this assessment probe with older students by asking them how they might measure the moon.   Consider the assessment probe from Uncovering Student Ideas in Astronomy (Keeley 2012, p. 95)


Asking students, “How far away is the moon?” also taps into their understanding of scale.  It also gives us a context to talk about the limitations of models and diagrams such as the image used at the top of this post.  Derrek Mueller at Veritasium has a video that elicits and explains this phenomena.

Below are the performance expectations from each grade band that could are connected to this phenomenal question.

First Grade: Use observations of the sun, moon and stars to describe patterns that can be predicted(1-ESS1-1)

Fifth Grade: Support an argument that the differences in the apparent brightness of the sun compared to other stars is due to their relative distances from the Earth. (5-ESS1-1)

Middle School: Develop and use a model of the Earth-Moon-Sun system to describe the cyclic patterns of lunar phases, eclipses of the sun and moon, and seasons. (MS-ESS1-1)