Sunlight and Shadows
Phenomenon:
Some days I see my shadow, and other days I don't.
Student Task:
Construct an explanation for what causes a shadow and why shadows sometimes disappear.
Model
Students develop and use a model to describe what causes a shadow and why shadows can disappear.
Investigate
Students plan and carry out an investigation to measure the length of a shadow at three different times during the day.
Obtain Information
Students read to obtain information about light and the sun as a source of light.
Analyze Data
Students graph and analyze the data they collect on shadow length to look for a pattern.
Explanation:
An object that blocks the sun's light makes a dark shadow. Shadow disappear on cloudy days because the clouds block the sun's light.
NGSS Standard:
1-ESS1-1. Use observations of the sun, moon, and stars to describe patterns that can be predicted.
[Clarification Statement: Examples of patterns could include that the sun and moon appear to rise in one part of the sky, move across the sky, and set; and stars other than our sun are visible at night but not during the day.]
Recommended Teaching Sequence:
Day 1: Students ask questions about shadows then give possible explanations for what causes a shadow to disappear. Students observe the weather on a day with no shadows and record observations in their science notebook.
Day 2: Students develop and use a physical model to describe what causes a shadow and try to make the shadow disappear. Students explain what causes a shadow then draw a model in their science notebooks to describe what causes a shadow to disappear.
Day 3: Students plan and carry out an investigation to measure the length of a shadow at three different times during the day. Students read to obtain information about the sun as a source of light.
Day 4: Students analyze the data they collected on shadow length to look for a pattern (i.e., that shadows are longest in the early morning and shortest at noonday). Students draw a model in their science notebooks to describe how the sun rises in one part of the sky in the morning, and sets in another part of the sky in the evening.
Formative Assessment:
Use what students have written in their science notebooks as a formative assessment, including
Do students understand that
Lesson Contributor(s):
April Mitchell, Science Specialist, Salt Lake City School District