North America will experience a solar eclipse “double-header” this fall. While 500 million people will see two partial eclipses (when the Moon covers part of the Sun), those fortunate enough to be in a 125-mile-wide path on October 14, 2023, will see an annular (ring of fire) eclipse of the Sun. Even more impressive, those in the roughly 100-mile-wide path of totality on April 8, 2024, will see a spectacular total eclipse.

Eclipses are rare and exciting celestial events that can produce a feeling of cosmic awe and mystery, but people’s sense of wonder can be enhanced through a clear understanding of what causes eclipses. Science teachers will be a key group for helping their students, schools, and communities with the eclipse preparation. The coming eclipse “double-header” provides a great hook to engage students in learning what causes the phases of the Moon (essential to understanding eclipses), how and when solar and lunar eclipses occur, and why people travel thousands of miles and spend thousands of dollars to see a total solar eclipse.

The eclipse and three-dimensional science learning

For educators, the eclipse and its associated concepts provide the perfect opportunity to incorporate three-dimensional (3-D) learning into your teaching, as recommended by A Framework for K–12 Science Education (National Research Council [NRC] 2012) and the Next Generation Science Standards (NGSS) (NGSS Lead States 2013). These documents describe three key dimensions of effective science learning:

1. Disciplinary core ideas (DCIs): The most important science and engineering ideas that students should know.
2. Science and engineering practices (SEPs): Behaviors that students need for investigating and building models and theories about the natural world.
3. Crosscutting concepts (CCs): Science concepts that have applications across all domains of science.

Traditional teaching strategies often focus only on conveying a specific DCI or using a particular SEP. The goal of 3-D learning is to interweave the dimensions, so students see them as a connected whole. Not every individual activity lends itself to incorporating all three dimensions; it is only when you look at a sequence of learning experiences that you can identify effective ways to incorporate 3-D learning.

Helping students understand what causes solar eclipses provides an ideal opportunity to connect a number of learning experiences over several weeks. The learning experiences described in this article use 3-D learning activities that focus on the middle school performance expectation associated with NGSS DCI MS-ESS1.A, “Develop and use a model of the Earth–Sun–Moon system to describe the cyclic patterns of lunar phases, eclipses of the Sun and Moon, and seasons” (NGSS Lead States 2013). At the same time, students engage with the following key SEPs:

• analyzing and interpreting data during their efforts to predict the order of the lunar phases and as they make regular observations of the Moon in the sky,
• using a model of the Earth–Moon–Sun system (light bulb, foam balls, and their heads) to describe the relationship between them and develop an understanding of what causes the Moon’s phases and eclipses, and
• engaging in argumentation based on evidence as they compare their predictions for the order of lunar photographs and their daily observations of the Moon.

The experiences we describe also allow educators to identify CCs embedded in the learning:

• Patterns observed during the experiences allow students to identify cause-and-effect relationships as they observe how the relative positions of the Earth, Moon, and Sun produce the Moon’s phases.
• Science assumes that objects and events in natural systems occur in consistent patterns that are understandable through measurement and observation, as students observe the Moon and Sun to understand when solar and lunar eclipses occur.
• System models provide an opportunity for understanding and testing ideas, which occurs when students use their head, a foam ball, and a light bulb to model the Earth–Moon–Sun system.

Note that it is not sufficient to just have students engage with these SEPs and CCs. It is critical that the teacher explicitly points them out as the kinds of concepts and practices involved in being a scientific thinker.

3-D learning in action

So, how does 3-D learning actually work in the classroom? The following set of learning experiences asks students to demonstrate their current understanding of lunar phases, before they learn what causes these phases, and then to extend what they have learned to gain a full understanding of solar and lunar eclipses. These activities come from our book, Solar Science: Exploring Sunspots, Seasons, Eclipses and More, available from NSTA Press (Schatz and Fraknoi 2016). Although step-by-step instructions are provided in Solar Science, some of these teaching strategies are also elaborated in other resources, such as the Astronomical Society of the Pacific’s The Universe at Your Fingertips 2.0 (Fraknoi 2011). The activities generally use simple items that are easy to obtain.

Initial engagement and pre-assessment

In this activity, students analyze and interpret data as they work in groups of three to five to examine and predict the correct order of six photographs of the Moon showing different phases (Figure 1). Students then develop their scientific argumentation skills by using evidence to explain their reasoning for the sequence they produced. Students’ predictions are posted on a classroom wall for ongoing reference as they make actual observations of the Moon over the next 10 to 30 days.

Observing the Moon to discover the order of the lunar phases

A major outcome of the previous experience is that students really want to know who has the right sequence for the lunar phases. This motivates them to go outside to observe the Moon. To determine the appropriate sequence—and orientation—of the photos, students must be able to identify a number of features on the lunar surface, so this activity also allows for a discussion of lunar craters and Maria.

This experience should ideally begin a few days before the Moon is at first quarter. The Moon will be in the western sky in the afternoon and evening, which will allow educators to take students outside near the end of the school day to make their first observation together. This daytime observation allows educators to review with students what each lunar observation should consist of, and gets them into the routine of making daily observations.

Students continue to gain experience analyzing and interpreting authentic data during their daily observations of the Moon. They use a simple observing chart (Figure 2) to identify the phase of the Moon, any surface features they can see, the time, and the location where they made the observation. If time constraints or the weather do not allow students to observe the Moon for a full month, they should be able to begin determining the pattern of the phases after about 10 observations. Daily observations are not necessary, so some days without observation should be fine.

After observing the Moon for 10 to 30 days, students discuss what their observations reveal about the phases of the Moon. Some of the key ideas that emerge are:

• Assuming you started a few days before the first quarter, the phases begin with a crescent Moon that has sunlight on its right side.
• More and more of the Moon’s surface that faces Earth becomes lit by the Sun over the next week to two weeks, until it is all in sunlight (full Moon).
• After the full Moon, less and less of the Moon’s surface that faces Earth is illuminated by the Sun, and the lit part is now on the left side.
• If students observed for a full month, they should be able to conclude that the time it takes one particular phase to appear again is approximately one month (29.5 days).
• Although the amount of light on the Moon’s surface that faces Earth changes throughout the month, the features on the Moon appear to stay in the same location.

A good evaluation experience is to give students another set of the lunar phases to put in order based on the new knowledge they have (Figure 3).

Students now have a good example regarding how objects and events in natural systems occur in consistent patterns, a CC of the NGSS. They are also at the first step of understanding the cyclic patterns of lunar phases, as indicated in NGSS DCI MS-ESS1.A.

Modeling lunar phases and eclipses

During the next experience, students develop their modeling skills to understand what causes lunar phases and eclipses. The model they use consists of students using their heads to represent Earth, a 60-watt light bulb at the front of the room to represent the Sun, and a small foam ball attached to a pencil to represent the Moon. The lamp is placed at the front of a completely dark room, and students stand facing the lamp, spread out enough so the light from the lamp reaches each student. (Safety note: Be sure to tell the students not to touch the hot bulb.)

Students are first asked to stand so it is noon in their hometown on their Earth/head. If they disagree about the correct position, students discuss it until they agree that noon is when their nose is pointed toward the “Sun.” Next, they stand so it is midnight in their hometown.

It is useful to remind students which way is north, south, east, and west for their Earth/head. If their hometown/nose is in the Northern Hemisphere, north is the top of their head, south is their chin, east is to their left, and west is to their right. From prior knowledge and their Moon observations, they should know that the Sun rises in the east. It helps to have students place their open hands on the sides of their heads, acting as horizon blinders (Figure 4). After some trial and error, they will be able to determine that Earth rotates from right to left in their model, with their right shoulder moving forward.

Students first practice rotating their Earth/head to determine how to stand so it is sunrise, sunset, noon, and midnight on their model Earth. They then add a Moon/ball to their model Earth–Moon–Sun system. They hold the model Moon at arm’s length and explore how the Sun’s light reflects off the model as they place their Moons in different positions around their Earth/head (Figure 5).

After students explore reproducing the phases with this model, they are asked to determine what position the Moon must be in its orbit to produce a particular phase. Full Moon is a good one to start with. Students are asked to compare their positions and discuss differences. Students then model other phases (e.g., first quarter, third quarter, new Moon, waning gibbous, waning crescent). When they have had sufficient time to explore producing different phases on their Moon/ball, students work in small groups of three to four students to complete a Moon Phases Activity Sheet (Figure 6).

Once students understand where the Moon has to be in its orbit to see each phase, the modeling continues as students explore where the Moon, Earth, and Sun have to be to produce solar and lunar eclipses. Students move their model Moon in its orbit to determine what phase the Moon has to be in to block the Sun’s light from reaching Earth (a solar eclipse) and when Earth can block the Sun’s light from getting to the Moon (a lunar eclipse). Through these observations, students discover that solar eclipses only occur when the Moon is in its new phase, and lunar eclipses only occur when the Moon is in its full phase. This is also the time you could discuss with them that the Moon’s orbit is tilted relative to the Earth’s orbit around the Sun, which is why we don’t get eclipses every month.

Students also continue to develop their ability to analyze and interpret data as they make observations of the phases in their model Earth–Moon–Sun system, and they use their argumentation skills as they use evidence from the model to compare and discuss their understandings of what causes the lunar phases.

3-D learning and the eclipse: Final comments

Becoming a proficient science learner is much like becoming a proficient tennis player; it requires practice. An important characteristic of 3-D learning is that the DCIs, SEPs, and CCs are not transmitted or acquired in a single activity. The dimensions require multiple experiences that introduce and reinforce them over time and in different contexts. Our series of lunar phase and eclipse experiences will expose your students to 3-D concepts, but lasting learning requires many additional science activities that provide 3-D experiences in other areas of science.

The beginning of this school year will be the best time to get your students (and their families) ready for the first solar eclipse in the upcoming eclipse “double-header.” You may have a second chance to get another group of students and their families ready for the second eclipse. We hope the ideas in this brief introduction and the information in the NSTA Solar Eclipse Observing Guide for Educators will inspire you to prepare your students for both the science and the delight of the eclipse.

If you and your students are in the narrow eclipse path for either the annular or total eclipse, congratulations! Your old friends and relatives will soon be discovering how much they long to visit you during the coming year. But if you are outside the path, there will still be a great partial eclipse to discuss, prepare for, and view safely. We wish you clear skies and prepared minds for the event.

ONLINE RESOURCES

NSTA Solar Eclipse Guide for Educators—https://bit.ly/3VxOtt3

NSTA Solar Eclipse webpage “Eclipse: Guides, Resources, and More”—https://www.nsta.org/eclipse

SUPPLEMENTAL MATERIALS

Lunar photographs, lunar observing record chart, and Moon phase activity sheet—https://tinyurl.com/2sba8dys

Connecting to the Next Generation Science Standards—https://tinyurl.com/4zxj5mn9

Dennis Schatz (schatz@pacsci.org) is Senior Fellow at the Institute for Learning Innovation. He lives in Seattle, Washington. Andrew Fraknoi (fraknoi@fhda.edu) is Professor of Astronomy at the Fromm Institute at the University of San Francisco. They are both leaders in the Solar Eclipse Task Force of the American Astronomical Society and in the project to distribute 5 million safe-viewing glasses (and information) for the upcoming eclipses through 10,000 public libraries, funded by the Gordon and Betty Moore Foundation.