How Can We Use a Model to Figure Out What Caused the Stick's Shadow Pattern?
Description:
Students review the stick's shadow pattern. Students are asked to use a model to figure out where the Sun was in the sky to create the shadow pattern they observed. ----------------------------------------------------------------------- Transcript: In the last video I said to trace the shadow of a stick five times throughout the day. What happened? Take a minute to review your shadows. Maybe talk about it with somebody. If you want you can pause the video. I'm going to show you what I saw. So here's what I saw: The longest shadow was at 8:30 in the morning and then the shadow got a little shorter at 10 o'clock in the morning, it got a little shorter at 11:45, it was the shortest at 1 o'clock in the afternoon, it got a little longer at 3 o'clock in the afternoon, and then it was longer again at 5 o'clock in the evening. You might remember that yesterday I started with the 10 o'clock shadow, but I came out here this morning at 8:30, and I was able to add this shadow then. See? I wonder, what made that shadow pattern? Take a minute to think about it or talk about it with somebody. You can pause the video. We know that shadows are created when the Sun shines on an object, and the object blocks sunlight to make a shadow. So, for example, the sun is shining right here on to the stick. The stick is creating a shadow right in that spot. So, if our shadow is moving, that must mean the Sun is changing positions in the sky. Let's make a model to try to figure out how the sun's position is changing in the sky. A model is not the real thing, but it's a representation of the real thing. And scientists use models to try to figure out how things work. I know! Let's use a flashlight to model the Sun. A flashlight is a good model of Sun because, just like the real Sun, it shines light. It's not exactly like the real Sun though, because the Sun shines light in every direction, whereas a flashlight only shines light in one direction. But, I think it'll work well enough for our model. Now, when I turn this flashlight on, I can't see anything! That's because the real Sun is so bright that I can't see the light from the flashlight. So, we're going to have to make our model indoors, which means that we need to bring our shadow pattern indoors with us. So you're gonna need a big piece of paper or a cereal box cut open like this. And, we are going to draw our shadow pattern and take it indoors with us. Move your stick onto your paper and trace around it. Now we're going to add the shadow pattern that we saw outside onto the paper. You don't need to write the exact times on the shadow pattern, but you can number them. See you inside! Here we are inside. I'm going to turn off the light and turn on my flashlight. I'm going to shine my flashlight on the stick, and try to make the same shadow pattern that we saw outside. In the next video we'll talk about how you moved the flashlight to create the shadow pattern that we saw outside.
