Flashlight Investigation

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SWBAT conduct an investigation to determine the effect of placing objects made with different materials in the path of a beam of light.

Big Idea

Light the way as your students explore how light travels in waves.

Instructional Notes

In the previous lesson, students planned an investigation about light.  Students chose the materials, including a flashlight as the light source and objects to see if light passes through or makes shadows.  Based on their questions, I used the responses to create two different recording sheets.  One is a chart format listing the materials in the left column and what happened in the right column.  The other is divided into four investigation questions.  I will introduce both options to students, and they can choose which they prefer.  Student choice is one way I create a student-led classroom culture.  

During the closing in today's lesson, student observations will be recorded under the "E" Evidence and Observations column on the KLEWS chart.  We will then use that evidence to arrive at our new learning "L" that light travels in waves and can pass through some (but not all) objects.

This unit is broken down into two main parts: sound and light.  This lesson investigates the question, "How do we communicate with light?"  This essential question incorporates two NGSS standards as we investigate the properties of light and also move towards the culminating engineering design product.

  • 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:



5 minutes

In the previous lesson, students put the materials they chose to investigate into bins for each table.  This makes today's set-up a breeze!  I have one bin per table, with lots of materials inside to investigate.  Students work in pairs with their "elbow buddy" during the experiment.  This allows them to have conversations and discuss the phenomena, as well as share their "aha" moments!  Sharing a flashlight also means one friend can manipulate the flashlight while the other manipulates the object in the beam of light.

Set-up video.

For the opening, I set the purpose for learning by reading the objective.

Friends, today we will be investigating what happens when we put materials in a path of light.  The path of light will be from our light source, the flashlight.  

Then, I review the light investigation recording options.

Let's look at the recording options.  First is a chart.  On the left is the material you are testing, like the wooden blocks.  On the right it says, "what happened."  We are thinking that we might see shadows and record it here.  But we also aren't sure what will happen with a few items on the list (like the mirrors).

The second recording sheet lets you make categories based on what you observe, and it gives you guiding questions.  Let's read them together.

I also remind students of etiquette while sharing materials.

Let's remind each other about how to share materials.  What will I do if I want a wooden block, but Luke has it? (ask politely, wait)  Let's all practice saying, "Can I please have ___ when you're finished?  Thank you."   

Exploration ~ the wave crest

20 minutes

During this time, the lights are off in the classroom in order to maximize the contrast between the flashlight and shadows.  I circulate and assist some of my developing writers with verbalizing their thoughts before writing and/or drawing what happened.  

Here are some questions I ask as I circulate:

  • What happened when the flashlight hit the _____?
  • How could we record that?
  • Could you make the shadow longer/shorter?
  • Could you change the shape of the shadow?
  • Why was/wasn't there a shadow?
  • What do you notice is the same about the materials light went through?

Here are students testing various materialstesting the sanitizer, and testing how the mirror reflects light.  Here is my check-in with a student who often needs help verbalizing his responses.

Having two response sheets worked very well.  This strategy allows students to decide how to progress through the investigation.  Do they want a chart, where they record each item line-by-line?  Or do they prefer a more guided question investigation?  Here are some samples of each:

Student work #1, 4-square

Student work #2, 4-square

Student work #3, chart

Student work #4, chart


5 minutes

At the end of our investigation, I play a transition song.  Students put their materials back in the bins and return to the rug.  I ask students to bring their observations and a pencil to the rug.  

Students share what they observed, and I record it on the KLEWS chart under Evidence/Observations.  As students share, other students can add to their recording sheets.  This is an important piece, because it gives students a chance to hear how others recorded and improve their own recording.

While students share, if we have any disagreements or questions, I have students grab the materials.  We retest right then and there to be sure of our evidence.

Finally, I have students come to the front with the materials that were transparent.  I ask, "What is the same about all of these materials and what happened?" (Light went right through them.)  I introduce the word transparent and we add it to the "S" Science section on the KLEWS chart.  Then, we continue for the objects that were translucent, opaque, and reflective.

We come to the bigger understanding, that different things can happen when materials are put in a path of light.

If time remains, we'll watch this video clip.  I find that video clips help students think about new information in an engaging way!  If there's no time today, I'll save this as an introduction tomorrow.