Science of Light

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SWBAT plan an investigation of light and shadows.

Big Idea

From shining them under your chin for scary stories to swirling light on the ceiling, flashlights are fascinating! Can we use flashlights for science too?

Instructional Notes

This unit is broken down into two main parts: sound and light.  Today we begin the second half, investigating the question, "How can we communicate with light?"  This essential question incorporates one NGSS standard 1-PS4-3 as we investigate the properties of light and also move towards the culminating engineering design product, 1-PS4-4.

  • 1-PS4-3. Plan and conduct an investigation to determine the effect of placing objects made with different materials in the path of a beam of light.
  • 1-PS4-4. Use tools and materials to design and build a device that uses light or sound to solve the problem of communicating over a distance.

Throughout this unit, I use a KLEWS anchor chart to record our new learning.  This is a science-specific type of KWL chart designed with primary students in mind!  Check out this video I like to call KLEWS chart 101:


In this lesson, we will plan an investigation about light.  In the subsequent lesson, our observations will be recorded under the "E" Evidence and Observations column.  We will use that evidence to arrive at our new learning "L" that light travels in waves and can pass through some (but not all) objects.


10 minutes

In today's warm-up, first I introduce the second essential question, "How can we communicate with light?"  To bridge the two sections of this unit, I ask, "What is similar about our two essential questions?  What is different?"  

Next, I highlight the word light in the essential question.  Under the K section (what we know), I write, "What do we know about light?"  I facilitate a class discussion.  As students share, I am looking for them to listen to one another and build on each others' ideas.  To help this along, I remind students of conversation rules and the concept of "piggybacking," or building and elaborating on one another's answers.  For example, a student might say, "I am piggybacking off of Mckenzie's idea that lamps make light.  I think it's the lighbulb inside."  We also sit in a circle around the perimeter of the rug so that students are facing one another.  In this way, it isn't a teacher-directed conversation, but rather it is a student-led conversation with teacher-as-facilitator.

To allow for an in-depth conversation, I lengthen the warm-up time.

As students share, I ask questions such as:

  • Do you agree or disagree?
  • Have other friends observed this, and if so, what else can you add?
  • How do you think we should record ____'s thinking?  (This question has student restate other students' ideas.)

I record ideas on the KLEWS chart.  Here is a section of our conversation.

If discussion in your room isn't flowing well (we all have days when students are tired, right?!?), try asking these questions to move the discussion forward:

  • What makes light?  
  • Where does light come from?
  • How come you can't see well in the dark?
  • What does light have to do with shadows?

After the conversation, or when it seems like we've introduced quite a few ideas, I have students turn-and-talk.  In a structured conversation, not all students get a chance to share.  Turn-and-talk gives them time to synthesize the ideas, use the vocabulary (like electricity), and restate their ideas about light.

In the conversation, students talked a lot about how we turn on lights and how light switches are connected to cords, connected to wires, and finally connected somehow to the wires outside.  One student added, "Is there electricity in the wall?", to the W section of the KLEWS chart.  The idea of electricity and power was not something I had planned to address in this unit, as it does not address the standards.  However, I plan to bring in additional free resources from our area electricity supplier to help answer student questions.

Exploration ~ the wave crest

20 minutes

In the Exploration, I want students to plan an investigation of the properties of light.  The NGSS calls for students to lead the planning process!  It is important to know about where you want students to go, so that you can lead the conversation towards an appropriate investigation, however, it is just as important to be flexible and allow student ideas to guide the process!

I begin with an introduction to set the purpose for today's learning.

Friends, to answer our essential question, we will be investigating light.  Today, we will plan ways that we can investigate light.  What does light have to do with shadows?  What could we use as a light source in a science investigation? (The overhead lights, flashlights, the sun)

Which of those light sources will work the best?  We want to use it safely at our seats and really be able to move the light around.  (flashlights)  If we use flashlights, should the classroom lights be on or off?  Why?

As we asked questions and had ideas, I recorded them on chart paper.  Here's the first half of our conversation.  Notice how students were asking questions too, like, "Are there shadows in the dark?"

Then, I continue guiding students towards an investigation of beams of light.  Here are some guiding questions for the discussion.

What could we do with the flashlight to show us how light travels?  

What kinds of materials do we predict will be good at making shadows?

Do we have other materials we could test that might have a similar result?

Do we have other materials that might get a different result?

Will light go right through any materials?

How would we draw to record light?

How would we draw to record shadows?

Is there any way we could sort the materials and make a table or graph?

I have materials in the classroom in mind, such as wooden blocks and cubes from our math kits, as well as small mirrors and plastic containers.  I also want to give students freedom to test beams of light on other objects they come up with in this discussion, or even during the investigation in the subsequent lesson!  Want to test your pencil-- go ahead!  

Here is the second half of our conversation.  One student shared that she notices shadows are longer at sunrise and sunset.  I turned this into a question, "Can we make shadows longer and shorter?"  And one of my students asked for a mirror this year, which is great because it will lead us to talk about reflective light.

The entire conversation chart is here.


5 minutes

For the closing, we make a list of materials to gather for our science experiment.  I have students gather the materials and make bins for each table.  I have found it is best to have students work in pairs with the flashlights.  This way, they are discussing their observations with one another.  Plus, one student can hold the flashlight while the other traces the shadow and object.  Table groups, though, share the testable materials.

While students go through their pencil bags, math manipulatives, and share ideas, I pull some other materials like glass marbles, straws, and the reflective safety mirrors.  I am glad that students have thought about their water bottles and sanitizer containers too, as that will move us towards defining translucent and transparent in the subsequent lesson.