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Body Conductivity

In these games and challenges, you’ll complete an electrical circuit with your body and explore ways to control the flow of electricity.

30 minutes to build your meter, 10 minutes to prepare your paddles, 1+ hour for activity

Warning: For these activities, we are using a very low-voltage power source that is safe to use. While we encourage you to explore and implement your own materials in these activities, we don’t encourage adding any more power or using other power sources that you aren’t familiar with; doing so may lead to injury.

Tools and Materials

Body Conductivity

Facilitator Note

In this activity, you’ll use an electrical conductor you know well—your own body—to complete a circuit and experiment with ways of changing your electrical resistance. But before you can play, you’ll need to build a conductivity meter to use with Science Journal. You’ll also need to make some conducting paddles to connect to your meter.

See: Build a Conductivity Meter

This guide was written to support facilitators leading others through the activities, with the following expectations. While it’s not necessary to meet all of these expectations, they will help give you a sense of where you might have to adapt:

Learners are at least 10 years of age.

You’ll need 5–10 minutes prior to doing the activity to download the app on one phone.

Both facilitator and learners are familiar with Science Journal and its Project, Experiment, Trial setup by going through the Getting Started activities.

The facilitator has run through the activities prior to facilitating. If this is not possible, we hope that a facilitator will do the activity alongside their learners to better understand what is going on.

The activity is designed to boost inquiry-based learning skills and scientific practices, not meet specific goals regarding the content.

Set Up: Make Your Conducting Paddles

Body Conductivity

To help connect your body to the circuit, start by making these conducting paddles. The paddles should be large enough for hands, feet, elbows, or other parts to touch with ease and flexibility. A wrapping of aluminum foil around the paddles allows your skin and the microcontroller to complete a circuit and send data to Science Journal.

1. Connect an arm’s-length piece of wire to your first lead on the breadboard using an alligator clip.

Longer wires help with giving you more mobility as you test later. Also, the longer the wire, the more people you can fit into your chain later.

Body Conductivity

2. Repeat this step again for your second lead.

3. Create and connect your paddles.

Cut a piece of cardboard in half. You can cut it lengthwise or crosswise, so long as both pieces are about the same size. Wrap both of your pieces of cardboard with aluminum foil. These will become your new contact paddles to test for conductivity.

Connect the two wires to your contact paddles via the alligator clips.

4. Test your paddles with Science Journal.

To do this, you’ll first have to pair your microcontroller meter setup to your smartphone using Bluetooth. Once you’ve connected, you can use either meter or graph modes to see your data.

When the paddles aren’t touching, the measured value should be zero. But if you connect them by stacking or overlapping, the electric current passing easily through the aluminum foil should give a value of 100%.

Try This: Hand Gesture Conductivity

Body Conductivity

1. Place your hands, palms down comfortably, onto the paddles and take a look at what value you’ve reached.

Observe your hands as they’re pressed to the paddles, and notice where your skin is making contact with the foil.

2. Press your palms down as flat as they can go onto the paddles, and see how the value changes.

Try going back and forth between loosely placing your palms and pressing them down harder to see and feel how your contact with the paddles affects your reading.

3. Challenge: How many different readings can you get by pressing your palms down on the paddles?

You can record your graph to document the range of values that you get by simply adjusting pressure. Remove your hands and wait a moment, then try again. Are the values you get the same every time?

4. Rub your palms together rapidly, as if you were warming them on a cold day, and then place them again on the paddles.

Do you see a difference in the reading? Small changes in moisture or sweat on your skin can lead to big changes in how conductive something is. What properties of sweat might be influencing these readings?

5. Place one finger on each paddle and have a look at your reading. Then add another finger.

Body Conductivity

Keep adding more of your fingers as you wish, or lift them away from the contact paddles. Using graph mode might help you see how increased contact or pressure between fingers affects conductivity. Is there a pattern or shape on your graph when you add or remove your fingers from the paddle?

6. As you change hand gestures and contact with the paddles, record your graphs and take notes.

Body Conductivity

Add titles to your trials and include notes that indicate what kinds of contact you’re making. Can you become adept at reaching particular numbers? You might want to ask a partner to take photos or notes in Science Journal while you do this and review them to improve your skill.

7. Explore one or more of these body conductivity games and explorations with others and take advantage of the different features of Science Journal.

Once you’ve tried them and feel comfortable, feel free to change the rules or come up with games of your own.

Tip

You can keep a cup of water nearby to explore an even wider range of readings in these activities. Rubbing even a single drop of water on your hands can lead to different results. Just be sure to keep water away from your microcontroller and smartphone.

Try this: Power Chain

Body Conductivity

Can your team reach a particular number on Science Journal through hand-to-hand contact? Can your team compete with other teams to reach that number first?

Start by giving each team one conductivity meter and one set of paddles. Set Science Journal to meter mode so you can see one value at a time.

To play, teammates connect through their hands to create a chain of changing gestures, with only the players on the ends touching the paddles. As contact changes, the value changes. Set triggers in Science Journal across each of the phones to the same number and play to see which team can reach a particular number, such as 35%. Can you hold that value for multiple seconds? How many other ways can you reach that same number?

Tip

To set Triggers in Science Journal, tap the three vertical dots in the top right corner of the sensor card to reach the available options. Add a new trigger, and choose the value you’d like, as well as what kind of notification to signal when you’ve reached the value. You can also set multiple triggers ahead of time to create a rapid-fire game of multiple targets.

Try This: Melodic Handshake

How do different handshakes look on a graph measuring conductivity? How do they sound?

First, find a partner and get set up with a conductivity meter (smartphone and microcontroller) and a set of paddles. Use graph mode to see how changing contact and pressure looks over time, and turn on the sonification feature to listen to the sounds of your graph.

To play, start with familiar styles of handshakes or friendly gestures, like fist bumps, pinky swears, “E.T. fingers,” or high-fives. How does each one sound? What do they look like on a graph? Next, collaborate on making up your own handshake, using Science Journal to see and hear the graph. Can you look at another team’s graph and guess their handshake?

Tip

Enable audio in Science Journal by tapping the three vertical dots in the top right corner of your sensor card, and enable the audio. Experiment with the different audio settings to produce different kinds of “instruments.”

Try This: Secret Handshake

Body Conductivity

Can you and your partner(s) work together to use changes in your conductivity to draw and recreate shapes on a graph? Can you draw shapes people will recognize?

To play, find a partner or team and get setup with a meter (smartphone and microcontroller) and a set of paddles. Use graph mode in Science Journal and assign someone to press the Record button as you explore.

Experiment and devise a changing pattern of contact—your “secret handshake”—then record your handshake as a graph shape. Or have someone else draw a graph for you and your team to recreate. Changing contact and pressure with your teammates over time will change the shape of the graph. Can you make a half-circle shape? A triangle shape?

Use the Record function in Science Journal to review your drawing and compare it to others. For an extra challenge, compete with other teams to see which can make the more accurate recreation of the graph that’s been drawn.

What's Going On?

Living tissues—including adorable you—are full of salty fluids that readily conduct electricity.

When you touch your hands to the conducting paddles of your conductivity meter, you become part of an electric circuit. You don’t notice the current passing through you, however, because it’s too small to feel.

The amount of electricity you conduct varies depending on your electrical resistance, and that number varies significantly. For example, the electrical resistance of dry skin is quite high, about 500,000 ohms. Soaked with sweat, however, skin’s electrical resistance drops significantly, to as low as 100 ohms.

Have you ever touched the top of a 9V battery to your tongue? If you have, you certainly remember the unpleasant feeling of getting “zapped” by the flow of current through your tongue. But you can touch the terminals with your dry fingers no problem—that’s the high resistance of dry skin working in your favor.

Increasing contact area also reduces your resistance, because it offers a wider “path” through which electric charge can flow. In the same way, thicker wires offer less electrical resistance than thinner wires, and are thereby more conductive.

Scales that measure body fat work by passing (tiny) electrical currents through you; it works because the fat, muscle, and fluid that make up your body all respond differently to these electric currents.