When following the Next Generation Science Standards (NGSS), middle school students are expected to answer the guiding question "...how can the motion of Earth explain seasons?" By using the science practice of modeling, this experience involves tracking the sun in a fun, hands-on way that will help your class understand this phenomenon.
What Your Students Will Learn
Getting students to grasp the reason seasons change based on the connection between the angle of sunlight hitting earth, earth's revolution around the sun, and the tilt of earth is tough. By marking the sun's shadow on a "sun tracker" one day per month throughout the year, students can collect data that they can easily analyze. This year-long phenomenon weaves the scientific practice of analyzing and interpreting data with the concepts of patterns, cause, and effect.
One of the reasons I love this activity is because it helps students understand the value of patience in the world of science. I also love it because it solidifies a concept that's quite literally beyond our reach: Sunlight traveling through outer space and striking earth.
Helpful Tips to Know
Review rotation, revolution, and the difference between geographic and magnetic north. Depending on the age of your students and your school's policy, students can also be directed to the National Oceanic and Atmospheric Administration's mobile app. The information it provides helps teachers construct the sun tracker and can help students understand how the sun tracker is used. It's also a good idea to practice using the tracker so you have a firm understanding of the activity and can help guide any struggling students.
Constructing the Sun Trackers
Prior to the lesson, you will need to construct a class set of trackers—one per four students should do the trick. Once materials are gathered, it should take about 30 minutes to make 10 trackers, and they can be used year after year.
Clear, fillable ornament balls that have a seam down the center so each half will become a dome for a sun tracker
- One piece of thin wood to be used as a base for each tracker
- A small compass for each tracker
- Graph paper
- Hot glue gun and glue sticks
- Wet erase pens to mark the domes
- Take one half of a clear dome and trace its circumference on graph paper.
- Make vertical and horizontal lines to represent north, south, east, and west.
- Record the magnetic declination (MD) and draw this angle to the right of true geographic north on the graph paper.
- Use a hot glue gun to attach the paper and dome to the wooden base.
Tracking the Sun
Walk students through the steps before they begin this outdoor activity, and explain how to mark the dome. It's quite simple, but it can be tough for some students to grasp at first.
- Place the sun tracker where there is plenty of sunlight and away from any shade that may appear throughout the school day.
- Place the compass on the base and line up the MD line to the north and south arrows of the compass.
- Move the wet erase pen over the dome (but not touching it) until you see the shadow of the tip of the pen over the intersection of the lines.
- When the pen is over the intersection, mark the dome with a dot at that location.
- Check for understanding and have students who understand the task help those who don't.
- Depending on the length of the class, you can make two dots. Students are always surprised at how quickly earth rotates.
- Don't move the trackers. Place a sign up to have students walk around them during passing periods and lunch.
- Repeat the markings of dots on the dome for each class.
- Don't wipe the dots off the domes. It's important for the students to recall the data from the previous month(s). By the end of the school year, the dome may be a bit messy.
The following day, students will record the full day's data into their science notebooks—a clear and accurate drawing will be sufficient. Eventually, students will create a model of their understanding, and a great extension of this activity could be an assignment where students explain why moss grows on the north side of trees.
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Students enjoy having this constant in the curriculum each month and having the longer length of time to analyze, discover, learn, and share their knowledge by creating a model. Just keep in mind that weather will inevitably be an issue, so turn this into a learning opportunity by having students determine the most probable location for that missing data. May the sun shine brightly on you and your students as you track its journey through the sky!