Me and My Shadow
Lesson 7 of 16
Objective: Students will learn about shadows and how they change throughout the day. They will also use shadows to learn that they are a result of the the earth moving, not the sun.
5E Lesson Planning:
I plan most of my science lessons using the BSCS 5E Lesson Model: Engage, Explore, Explain, Elaborate, and Evaluate.For a quick overview of the model, take a look at this video.
I use this lesson model because it peaks the students' interest in the beginning during the "Engage" portion and allows for the students to actively participate in the investigations throughout the subsequent steps. The “Evaluate” component of the 5E Lesson Model can be used in many ways by the teacher and by the students.
In this Unit students will learn about the solar system by studying the sun, the moon, planets and stars. In the first three lessons the students will learn about the Sun. Lessons 4 through 7 focus on the movement of the Earth around the Sun. Lessons 8 and 9 are lessons about Orreries, lessons 10 and 11 cover solar eclipses, lessons 12 and 13 are about the moon, lesson 14 discusses the other planets in the Solar System, and the last 4 lessons (15-18) are about stars and constellations.
Lesson Overview: This investigation was done over 2 days, but could be done in one day if you have the exploration and elaboration sections done on the same day. This is an outdoors lesson and of course will be based on weather and cloud cover.
Next Generation Science Standards:
The NGSS standard that will be covered in this lesson is:
5-ESS1-2 Represent data in graphical displays to reveal patterns of daily changes in length and direction of shadows, day and night, and the seasonal appearance of some stars in the night sky.
Disciplinary Core Ideas:
This lesson aligns to the Disciplinary Core Ideas from the Earth and Space Science:
ESS1.B: Earth and the Solar System. The Earth’s orbit and rotation around the Sun,and the orbit of the moon around the Earth cause observable patterns.
Similarities and differences in patterns can be used to sort, classify, communicate and analyze simple rates of change for natural phenomena. (5-ESS1-2)
Natural objects exist from the very small to the immensely large. (5-ESS1-1)
Science and Engineering Practices Almost all of the Science and Engineering Practice are covered in this unit. Click the link to see them listed.
To start this lesson, I have the students write the question "What is a shadow?" in their science notebooks and they write a sentence or 2 about what they think a shadow is. I then take the students out to the playground area where there is plenty of space. We have a large basketball court and this is a great spot for the activity. It's important to do this on a clear, sunny day. It's also important to remind the students to not look directly at the sun. The morning is also a good time to start this activity since the students will observe their shadows throughout different parts of the day.
I ask them about what they think a shadow is and have them to look at mine. Some students think that it is a "reflection" or "picture" of me and I explain that it is really an outline of my body that is caused by the blocking of the rays of the sun by my solid figure.
I then tell them to look around to try to discover other shadows and then to look at and explore their own shadows. I encourage them to change the shape of their shadows.
After a few minutes of exploring our shadows, I ask the students what they learned:
" It does what I do", "It follows me everywhere", "It looks just like me, except it's not in color", "It doesn't have a face or eyes", and "It doesn't have a lot of detail."
I make sure to clarify that it won't have the details that they have since it is blocked light from the sun. I then have the students record their observations in their science notebooks by drawing or writing about the experience.
After the shadow exploration, I have the students draw a table in their Science Notebook to record their shadow lengths during the shadow investigation. I then give directions to the students about how to trace and measure their shadows. We use measuring tapes to measure the length of the shadows from their heels to the tops of their heads and the unit of measure we use is centimeters.
I divide the students into groups of 3 so that it will take less time to trace shadows onto the blacktop. We make sure to spread out so that everyone has enough space for their shadows. We use regular chalk for the tracing, but sidewalk chalk would work better since it doesn't break as easily. I tell the students to first trace their partner's feet so they know where to stand when they trace and measure the other shadows during the day. As one student stands to have their shadow traced, the other 2 students draw the shadow.
They then measure from their heels to the tops of their heads using a measuring tape. As they do this, they realize that the measuring tape doesn't reach the whole length and I tell them to make a mark where the tape measure ends, write this measurement and then measure the second part. They then add these numbers to get the total and record it in their Science Notebooks. Here's a photo of Students Measuring Shadow Length
I then tell the students to compare the length of the shadow to their own height. I give the kids a choice of either laying on top of their shadow to compare their height to the shadow's length, or they can measure their height with the measuring tape and compare this to the length of their shadow. I have the students compare their height to the shadow so that they can see that the shadow is their body blocking the light from the sun and that their actual height is shorter than the shadow length. They see that this changes throughout the day, depending on the position of the Earth. I also tell the students that they can use their shadow length and their height to figure out the heights of taller object that would be harder to measure (a few students asked about how tall the basketball hoop was). I tell them that we will learn about proportions in a later math lesson and this data will be useful when we work on this lesson.
We will also do the same procedure at approximately 12 pm the same day and again at 2 pm so we can compare the 3 lengths of shadows. These times and measurements are also recorded in their science notebooks.
After the students have recorded the 3 measurements of their shadows we return to the classroom to discuss our findings and to graph our data. (Since our last recording was done right before school got out we did this the following day.)
The students create a graph in their science notebooks to represent the data they collected during the investigation. We decide that a line graph would be the best way to do this so that we can see the changes in the lengths of the shadows. I tell the students to also draw their shadows from the playground so that they can see the different directions each of their shadows had. They create this drawing on the page they did their original shadow exploration on in their notebooks.
We look at the data and discover that all three shadows have different lengths. We then have a discussion about why this happens. In our discussion, the students realize that the changes to the shadows occur because of the position of the Sun compared to the Earth and that this is caused by the movement of the Earth (its rotation) and NOT the movement of the Sun, as many students believed. They also notice that the shadows are longer when the Sun is lower in the sky (morning and late afternoon) than when the Sun is directly overhead (noon). Here is a Student explaining the changes to the shadows. I did have to remind her again that it was the movement of the Earth and not of the Sun.
I also reminded them of our previous lesson about What Makes Day and Night? and they remembered that is was the movement of the Earth, NOT the movement of the Sun that makes night and day.
For the evaluation portion of this lesson, I checked what the students wrote in their Science Notebooks for their summaries for the investigation. I notice that several students write that their shadow lengths change throughout the day with the morning length being the long, the midday shadow being short and the late afternoon shadow being long again. Here's a Student notebook entry- Shadow Summary.