Let There Be Light

Challenge
There are two moments in the year when the Sun is exactly above the Equator and day and night are of equal length. Do you know those two moments? Hint: One of those days is coming up this month. If you mentioned the first day of spring or autumn, you would be right with spring being the day this month. We call these days equinoxes, and in March, it’s the Spring or Vernal Equinox. Vernal means relating to spring and to understand equinox, we can look at the word origins. Equi comes from the word “equal” and nox is a Latin word for “night”. Equal, night which describes what happens on the Vernal Equinox.
​
Your challenge this month has to deal with collecting data with sunlight and shadows. Set up an item near a window where the Sun shines or outside. Do not move this item once it is in position. Measure the length of the shadow at the same time of day for the month of March and record the data. Also, collect data for the amount of daylight and darkness for everyday in March and graph the results (https://www.timeanddate.com/sun/ is a great resource for this data collection).

After the data is collected, your real challenge is to analyze the data in order to look for patterns. What do you notice about the shadows and daylight/darkness hours? What day was the Spring Equinox? What does this data mean or show with the Earth’s revolution? Why are the shadows changing length? When will the patterns noticed about the shadows change? When will the hours of daylight/darkness pattern change?

Materials

• item to cast shadow
• measuring tools (ruler or strips of paper)
• notebook for data collection
• chart paper for making graphs and recording data

​
Hints and Tips for Success

1. Allow students planning time for how they are going to set up their item that will cast the shadow, what time they will measure the shadow, how to measure the shadow, and how they will collect and display the data.
2. Allow students planning time for how they are going to collect the data about daylight hours and darkness hours, display the data, and graph the data.
3. Students could collect shadow data by using strips of paper for each day and hanging them side-by-side for comparison. These strips could also represent the bars on their created bar graph.
4. Students could also display their daylight and darkness hours using graph paper with each square representing an hour. Students could make a bar graph out of these strips of paper for comparison and easy graphing.
5. Make sure to standardize the shadow measuring by collecting the data around the same time of day. Collecting the data around noon might work best. On the day following a weekend or days not in school, measure the shadow and ask students to estimate the previous days’ length based on their data collected thus far.  
6. Connect to math by discussing graphs, data collection, telling time, elapsed time, units of measure, etc.
7. Connect to science by discussing sun patterns, reasons for the seasons, rotation and revolution, day and night, lengths of shadows, etc.