Why Does my Shadow Change? Day 1

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Objective

SWBAT build a model to determine how a shadow changes throughout the day.

Big Idea

Students build a model to investigate how the position of the sun affects a shadow.

Rationale and Preparation

The Why Behind Teaching This 

Unit 6 teaches students about Earth's Place in the Universe.  Standard 5-ESS1-1: Support an argument that differences in the apparent brightness of the sun compared to other stars is due to their relative distance from Earth, is one standard covered.  Standard 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, is the other standard covered.  

Throughout this unit, students will learn about classifying stars, patterns of stars, and the effects of rotation and revolution.  We will be creating models, graphing data, tracing our shadows, and much more.

This specific lesson covers standard 5-ESS1-2 by having students build a model to investigate how shadows change as the position of the sun changes.  Students will use their model to calculate how the direction and size of the shadow changes as the position of the sun changes. 

Lesson Goal:

The goal of today's lesson is for students to build a model to use to investigate how shadows change as the position of the sun changes. 

Success Criteria: 

Students will demonstrate success by correctly completing their model to be used with the next two lessons.  

Preparing For The Lesson:

Warm Up:

  • Flashlight for making shadow puppets

Guided Practice:

The following materials are needed for modeling as going through the directions

  • light colored paper
  • 1 square of cardboard
  • 1 quarter or washer 
  • tape 
  • cardstock  
  • straw 

Explore:

The following materials are for groups to use to build their model. 

  • light colored paper
  • 10 squares of cardboard 
  • 10 flashlights 
  • 10 quarters or washers 
  • 10 measuring tapes 
  • tape 
  • cardstock  
  • straws 
  • copy of the Shadow Investigation Sheet for each group 

Wrap Up:  

Students will be sharing their observations so no other materials 

Warm Up

10 minutes

Shadow Puppets 

I begin the lesson today by turning off the lights and having a student hold a flashlight pointing at the overhead screen while I make a shadow puppet.  After students guess what the animal is, a duck, I allow a few students that want to try, to come up and make a shadow puppet.  

                                          

After a few students make shadow animals and the rest of the class guesses what they are, we discuss this activity.  I ask students, how were the shadows projected onto the screen.  They tell me the light of the flashlight.  I ask them to give me more information, by asking another leading question. Why are the shadows dark, if they are created from light?  Their answer is because the persons hands block the light so it is projected around the hands, but not where the hands are.  

Why Begin With This Activity 

I begin the lesson with shadow puppets because it is a fun way to introduce the discussion of shadows.  The students enjoy making the shadow puppets and guessing what other students have made.  Through the discussion that follows, I am able to get students to begin thinking about how shadows are produced.  It allows me to make sure they understand the basic concept of how they created before we get into the more difficult concept of shadows created from sunlight, and how they change as the sun moves across the sky.  

Guided Practice

10 minutes

Directions for Building the Model 

I explain to students that we will be building a model that they will use to investigate how the position of the sun affects their shadow.  After investigating with the model, they will then do the same investigate outside to test how accurate their model was compared to their real life shadow.  

I begin going through the steps to building the model so students will be able to create one on their own.  While I go through the steps, I hold up the materials being used and model what each step will look like.  This helps ensure the visual learners will be successful.  If I notice any student not watching, or following along, I randomly call on them to repeat the last direction I just gave.  This helps ensure that students stay focused and keeps me from having to repeat directions later.

  • Cover a piece of cardboard with a light color paper and tape it down on the bottom side of the cardboard. 
  • Mark one side North, East, South, and West
  • Find the center of the board by measuring the width and length, mark the location with an X.
  • Create a figure of a person that is between 3 - 5 inches tall. 
  • Tape it onto a metal washer and if needed tape a small piece of straw to the back to help support it. 

I show a model that I have already completed so that students know what a completed product should look like.

  

Explore

30 minutes

Building their Models 

I allow students to choose a partner for this activity.  This activity stretches over a 3 day period so it is important that they work with someone they know they can get along with and work well with. I remind them of the importance of choosing a partner they work well with and will not be playing around with.  I do have a couple of students that I know play around when together so I am proactive and tell these students they cannot work together and should choose different partners.  

Once all students have a partner, I provide each pair with materials and they begin building.  Students spend the next 15 - 20 minutes building their model.  

How Does Our Shadow Change When We Face Different Directions? 

The last 10-15 minutes of the lesson, students use the model to complete the first investigation on the Shadow Investigation Sheet.  I want them to do one easy investigation today so that I can ensure they understand how to use the model and complete the lab sheet.  I go over this investigation with them step by step as they record their observations.  The investigations in the following two days will be completed independently.  

The first investigation is testing how the shadow changes when the person is facing different directions.  I read the directions from the lab sheet and point out the diagram next to  the directions.  I point out the black oval in the center and explain that this represents their person.  They should place their person in the center of their board on the X they marked.  The person should be facing East to begin with. I wait while students set this up and check for accuracy.  I show that the arrow in the diagram represents the direction of the light.  The flashlight should be held from 150 cm away, in the position pointing light similar to the that shown in the diagram.  150 cm is the full length of a measuring tape so it is easy for students to get it in the correct position.  One student holds the flashlight at 150 cm, pointing towards the model as illustrated in the model.   

Before groups begin the investigation I ask them what they are changing in this investigation.  They tell me the direction the person is facing.  I remind them that this is the only thing that should be changed.  The light should always be held in the same location, at the same distance, and the person should always be on the X, they are just rotating them to face different directions.  Students begin the investigation by observing the shadow made as the person faces East.  They then rotate the person to face South, West, and North, and observe how the shadow changes.  They record their observations in the lab sheet.  I circulate to observe groups working and ask questions to ensure they care understanding what is occurring.  As you can see in the video of group testing how the direction a person stands affects the shadow, I ask the girl what affects the direction of the shadow and she is not able to tell me.  Her partner holding the flashlight gives the correct answer.  This is the conversation I want to encourage while they are working in small group. 

Wrap Up

10 minutes

Sharing Information 

Groups share the observations they recorded on their lab sheet.  All groups found that the shadows were all long, some groups measured and others did not.  Those who measured found that they all stretched about 68 cm.  For this investigation I simply put to record a description so I wasn't really looking for specific lengths but some groups saw that length was listed for the other investigations so they went ahead and measured for this one too.  

The difference that was noted by all groups was the thickness of the shadow.  They found that if the light is coming from the East, the shadow is thickest when the person is facing east and west.  They found that the shadow is very thin when the person is facing North and South.  Since they are using cardboard cutouts to model a real person, the cardboard is thinner than any person so we will see if this turns out to be accurate when they compare their findings to real world shadows in day three.