Light Instruments: Designing and Building

Design and build a musical instrument that responds to changing light.

At least one hour and twenty minutes. 15–20 minutes to set up the microcontroller, 10–15 minutes to set up your craft materials, and 45+ minutes to design and build.

Here you’ll apply what you learned in Discovering Shadows to build your own light instrument. “Instrument” here has a double meaning—it can be a device for measurement or for making music. In this activity, you'll make one thing that does both.

Tools and Materials

  • Download the Science Journal app
  • Battery and battery connector
  • Cardstock (various colors)
  • Chipboard
  • Craft sticks (large and small)
  • External sensor (light sensor board)
  • Flashlight
  • Hot glue gun
  • Hot glue sticks
  • Markers
  • Masking tape
  • Metal rod
  • Microcontroller (Bluetooth capable)
  • Microcontroller base
  • Paper cups (small)
  • Pipe cleaners
  • Puck
  • Scissors
  • Straws
  • String
  • Wooden skewers

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Note: For this activity we recommend switching from the Ambient Light sensor in the phone to an external photoresistor. (See setting up the photoresistor.)

Using an external sensor makes it easier to document and record your results, and also reduces the likelihood that you’ll cast unwanted shadows with your hand as you use the app. The external sensor is also more sensitive to light changes and will give more accurate readings than your phone’s light sensor. Note that the units displayed on the app will appear not as lux, but as a percentage of the maximum lux detectable. You might want to try some of the Getting Started activities again using the external photoresistor to confirm it works more or less the same as your phone’s light sensor.

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Instrument Building Warm Up

Get your creative juices flowing by experimenting with limited materials.

1. Gather two sheets of paper (plain white works best), scissors, masking tape, and your microcontroller setup.

Connecting your microcontroller to your phone might take a few minutes.

2. Enable audio on Science Journal and place one sheet of paper over the external light sensor.

What reading and tone do you get?

3. Fold your sheet of paper in half and place it over the sensor.

Has the reading changed?

4. Fold your sheet of paper in half again and place it over the sensor.

What’s different?

5. Now carefully unfold and refold the sheet of paper over the sensor and listen to what happens.

Record your trial a couple of times. Play back your recordings and watch the graph.

6. Use your second sheet of paper to experiment with other types of alterations that could give you different readings. Try “playing” your piece of paper like an instrument to make musical sounds.

First imagine all of the possible things you can do to manipulate the paper, from cutting to crumpling to rolling it into a tube. What other ways can you change the paper to affect the light levels/sounds?

Instrument Building

Design and build a musical instrument that responds to changing light.

1. Brainstorm the different ways you’ve experienced that light levels can change.

Questions you may ask:

Which variables change the amount of light hitting the photoresistor?

How many variables can you think of? Try brainstorming questions that start with “What happens if . . .?”. This exercise will give you a list of variables to investigate. For example:

  • What happens if I cover the photoresistor with a piece of red paper?
  • What happens if I move the red paper 1 cm away from the photoresistor? 2 cm?
  • What happens if I move the red paper slowly? Quickly?
  • What other “What happens if . . .” questions can you think of? The list is limited only by your imagination and the materials on hand.

It helps to show demos of possible instruments. Either make some examples beforehand or use these videos as samples.

  • Musical Score Instrument

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  • Wearable Instrument

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  • Self-Playing Instrument

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  • Flute-like Instrument

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  • Mechanical Instrument

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Build an Instrument

2. Build an instrument that allows you to control just one variable.

Choose one “What happens if . . .” question to investigate. For example, what type of instrument would you build if you wanted to change the distance of an object from the sensor? Focusing on one factor will help you understand which tweaks you can make to produce different results.

Test It Out With Science Journal

3. Once you’ve built your instrument, test it using the Science Journal app.

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Create a Project within the app and give it a name (e.g., Light Instruments), then set up an Experiment and give it a name (e.g., Blue and Yellow Cups Design 1, or, Hand Castanets Design 1).

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Document your instrument using the notes feature (remember you can snap a pic).

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Test your first iteration and record the results. You can play back your results when you review the trial run.

Try changing a design element and creating a new Experiment for these tests (e.g., Blue and Yellow Cups Design 2: With Holes, or Hand Castanets Design 2: With Multicolored Bottoms)

Choose another “What happens if . . .” question and design a new instrument. Set this up as a new Experiment in Science Journal.

Record different trial runs with the new adaptations. What do you notice?

Going Further

Challenge yourself. Brainstorm a list of questions that start with “Can you find a way to . . .?” For example:

Can you find a way to make a three-note instrument?

Can you and a partner find a way to create two instruments that play a song together?

Can you find a way to turn the whole room into an instrument?

What other challenges can you come up with?