Let's Get it Straight

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Students will be able to discover that the path of light is a straight line.

Big Idea

This lesson will engage students in experiments that will define the path of light. This must be covered before we can explore how we can use light in different ways and how light responds.

Motivational Warm Up

5 minutes

Yesterday, we learned about Thomas Edison and some of the character traits he possessed that helped him become such a successful scientist.  Today, to begin our session, I will ask the students to vote on one of the 4 quotes in the book by Thomas Edison to represent our class and then we will hang it.  The quote, "If we did all the things we are capable of doing, we would astound ourselves." will hang above our door all year now!

Then, I gave the students a blank cut-out of a light bulb and prompted them to write, "I am like Thomas Edison because…" and fill in the blank using the information they had learned about his personality traits. 

These light bulbs will be placed around the perimeter of the quote in order to constantly remind the students that they possess qualities just like one of the most successful scientists that we know. 


5 minutes

Today, we will be discussing the path of light, so obviously, our question for the day will be, "How does light travel from its source?"

To engage the students, I will give each partnership a flashlight and ask them to explore our question, as I darken the room as much as possible. I will tell the students I will alert them when 2 minutes is up so they can switch partners. 

After 4 minutes, I will call the students back to the community area to listen to their findings. While listening, it will be crucial for me to identify misconceptions in order to clarify during the remainder of our science sessions. 


Mini Lesson

10 minutes

While the students remain at the community area, I will ask them to get into a fishbowl formation so they can observe myself and another student explore the supplies on our tray in order to determine how light travels. 

The tray will contain: a flashlight, 3 index cards with various numbers of holes punched in the center of them with a hole punch, an index card that is solid, pieces of modeling clay, and two small mirrors. I will also show the students how to put the index cards in the modeling clay to keep it still and how to put the blank card behind it at a distance to mark where the light hits. 

I will model with my student partner how to ask our "wondering questions" in order to create an investigation to determine what type of path light takes. 

Some of the questions I might model are: "Can we make light move around a corner? What could we use on the tray to see if it can bend?"  "What would happen if we shine the light on the index card with one hole? Where would the light end up?"  "If we shine the light on the mirror and move the mirror, what will happen to the light?" I will, of course, also ask my student partner to ask some questions that we can explore as well. 

During all of this modeling, I will show students what I mean, but I will refrain from letting them see the results by not turning on the flashlight. I don't want to take the excitement of the results away from them!

Active Engagement

25 minutes

Following our modeling, I will have the science partnerships collect a tray in our science center and begin their work. Many students immediately began working with the mirrors, as the reflection caused the most excitement.  However, others went systematically through the index cards and worked to figure out if light paths changed based on the number of holes. 

This group was sparked by a question one of the members had and went into many experiments to figure out an answer. 

Along the way, they came up with even more questions. How scientific of them!

In this video, my students began investigating ways to use reflection to make light travel to a predetermined location.  Notice the "X marks the spot" on the index card. This was a wonderful exploration and I will leverage this experiment later in our lessons. 

Closing and Sharing

5 minutes

As a closing, I will show this short video of a student far away from us in order to show my students that they were able to devise an experiment without being told how to do it.  This will, once again, confirm their identity as scientists.