Rainbows, kaleidoscopes, fun house mirrors... what do these things have in common? They're both caused by two natural phenomena: reflection and refraction.
You know that reflection happens when light hits something and bounces right back, like when you see yourself in a mirror. In contrast, refraction occurs when light travels through different mediums and bends, such as how a straw appears bent in a glass of water.
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These might sound like challenging concepts to teach, especially for elementary students, so I have a few hands-on activity suggestions to help "light up" your younger learners:
🌈 Making a Rainbow in the Classroom
Objective: Refraction
Materials: Beaker of water, sunny day
Activity: When sunlight encounters raindrops, it refracts, reflects off the back of the droplet, and refracts again as it exits. This transforms light into a beautiful spectrum of colors—red, orange, yellow, green, blue, indigo, and violet.
You can replicate this event with a beaker filled with water. If a student slowly raises the beaker in front of a window facing bright sunlight, a rainbow should be projected on the floor. Students can place white printer paper where the rainbow is projected to trace and color the light. Does a real rainbow show the same spectrum of colors?
🪞 Mirror, Mirror on the Wall
Objective: Reflection
Materials: Small mirrors, flashlights, protractors, and paper
Activity: Discuss how the angle that light strikes a mirror is the same as the angle the light reflects away. Students place paper on their desk and set up a mirror directly on the flat surface. Without turning them on yet, students position flashlights to point at the mirror at a certain angle. They can draw a straight line on the paper to predict how the light will travel.
Using a protractor, you can have students draw line coming off of the mirror from the same, but opposite, angle. Hit the lights and let students shine their flashlights. 🔦How close are their predictions? What happens when they make the angle larger or smaller?
✏️What Happens When Light Bends?
Objective: Refraction
Materials: Clear glass cups, water, pencils, and markers
Activity: Fill cups with water and place a pencil or straw in them. Watch as the object appears to bend at the water’s surface! Can students measure the distance between the actual straw and the image of the straw? Which direction does the light move compared to the actual object? How might this be helpful information the next time students go fishing? 🎣
Pro tip: Students can make a labeled drawing including their measurements. Sketching this can be therapeutic, like a nature doodle!
🌈 DIY Kaleidoscope
Objective: Refraction
Materials: cardboard tube, tape, foil or silver cardstock, scissors
Activity: Students can build a kaleidoscope to see the effects of refracting light. Start with a cardboard tube, like a toilet paper roll. Next, you'll want to cut out a rectangle of your foil cardstock. If you can't get your hands on the foil cardstock, you can always glue some foil onto regular cardstock. The images might be a little blurry, but it'll still be a functional kaleidoscope.
If you're using a toilet paper roll, cut out a 4 in x 6 in rectangle of reflective cardstock. Now, fold the paper lengthwise into three equal pieces, each 2 in wide. Push the sides together to make a triangle that is 4 inches long and tape the top. This will fit nicely into the toilet paper roll.
You can use this setup alone to view materials into your classroom and get a cool kaleidoscope effect. If you want to level up your kaleidoscope a little more, put a zipped plastic bag of beads at the bottom. Your students now have a refracting light show in their hands!
Give some of these project ideas a try and let me know how they go!