What Makes for an Effective Science Demonstration?

by Laura Henriques

You are standing at the front of the classroom, poised behind some apparatus. Students are watching expectantly. Something exciting is about to happen, but what? The tension in the room is palpable as students eagerly await the moment when you make the magic of science come alive. You make a motion to start the demo and then pause, pulling the students along with you to further build the anticipation. When you do the demonstration and it works you have their attention, you’ve piqued their interest and they are ready to learn.

This happens in your classroom every day, right? It could! Science demonstrations have the power to engage our students in a variety of ways. The ways in which we use our demonstrations make all the difference in the world.

Demonstrations can serve a variety of purposes. I had a friend who started every single day with a quick demo. He did them only once, and right as the bell rang. Students were required to write a brief description of what they saw and what they thought was going on. This was his daily warm-up. It was great for getting kids to class on time as he only did the demonstration a single time – if you were late you missed it and you weren’t able to get points for the warm-up without having seen the demo.

The same demonstration can be used multiple times for different purposes. At the start of a class or lecture, they can serve as a common experience to which you refer back to during class. On the other hand, if used at the end of an instructional segment they can illustrate a concept just explained. During the middle of instruction a demonstration can be used to review content or introduce new ideas. They can prompt lively discussion or be the prompt for a quick write.  Some may choose to combine these approaches, for example, doing a demo at the start of class to pique interest and provide a shared experience, then repeating it again after some learning has taken place so that students can apply what they have learned as they try to make sense what happened. Demonstrations can also be motivational, giving students a reason to pay attention, read and learn. Discrepant events are really good for that purpose as they captivate student interest because of their unexpected results.

More often than not, we shouldn’t spend too much time explaining during the demonstration. You will have time after the demonstration to ask questions and teach content. Silence is golden for some demonstrations. It builds the drama and focuses attention on the phenomena. Sometimes we do demonstrations to teach a particular skill. In this situation you will want to explain while you demonstrate.

Here are some tips to consider when doing science demonstrations.

1. Prior Practice Prevents Poor Performance. A teaching buddy of mine used to drill into me these “5Ps of science demos” (and labs). We have to try them ahead of time. Know how it works, be comfortable with it and be aware of the tricks needed to make it work well. Demonstrations do not always work the first time we do them. Being comfortable with the materials enables you to be confident and comfortable in front your class. If it does not work as expected during class you’ll feel better about setting it up and trying again. (As an aside, don’t spend too much class time trying to make the demo work if it has failed a few times.)
2. Don’t tell us what is going to happen before you do the demo. If you take away the element of surprise by telling us exactly what to look for and what to expect (and why) then you don’t really need to take the time to do the demonstration. Consider doing the demo without any explanation at all as a way to engage the class and pique their curiosity. This creates a teachable moment – students have seen something and now they want to know how and why it works. After the explanation you can do the demo again, this time talking about what is going on while performing the demo.
3. Make sure people can see! You won’t want to go to all the trouble of putting together a demonstration if your students can’t see it well. Think about how the demo will look from the back of the classroom. Is it big enough? High enough off the lab table so that all can see? Does it need a solid background to be easily seen? Perhaps you need to use a document camera to project the demo so all can see it, or you need to raise the entire demonstration by putting it on a pile of books or a box so kids in the back can see. Maybe it would be more visible if you put it on the overhead and shined light through it or projected it. If you are doing something which relies on color changes it won’t help if you are wearing a multicolored shirt, maybe you need to hold up a piece of white paper behind the apparatus.
4. Consider getting students involved in the demonstration. Some demos need an assistant or a shill. Enlist the help of your students! Some of the demos are easily replicated with common materials. Consider having students try the demonstrations at home, to teach family members. Not only does this get the kids talking about science with their families, it helps them verbalize what they know as they are explaining the science. Teaching the content helps them learn the content.
5. Consider recording your demonstration. Some demonstrations are very time consuming to set-up. Some take place really quickly. Some are a bit persnickety and don’t always “work” exactly as planned. For those demonstrations it can be helpful to record the demo and show it in class. This method allows you to watch the demonstration in slow motion, pause at key points (to ask questions or reiterate key points), and you can watch the demo over and over without having to set up the equipment again.
6. Showmanship matters! Not all of us are comfortable being goofy in class, but doing so can make a big difference. Compare these videos of the same demonstration. While we aren’t as funny or talented as Dom Deluise, we can all ham it up a little to build tension and build interest. The demo is exciting all by itself, but Dom Deluise gets the viewer (student) more involved and invested by pretending to be nervous about the outcome.

Mrs. Dowdle’s Inertia Eggs   (http://www.youtube.com/watch?v=B20GRM64JU8)

Dom Deluise on Johnny Carson (http://www.staged.com/video?v=4Vkc)

Doing demonstrations in your science classroom does not take the place of doing labs or activities, but they can greatly enhance your instruction. Try some and see how they work. If you find a collection that work well, consider sharing them with your colleagues at the CSTA Conference in 2013 or via an article in eCCS! I encourage you to share your favorite demo via the “comment” box at the end of this article so we can all learn from each other.

An Invitation

For those of you who teach physics or physical science in the LA area, California State University, Long Beach hosts a monthly Physics Demo Day. The 2^nd Thursday of each month from 4:30-5:30 p.m., we gather to share our favorite physics demonstrations. Topics vary each time as we move through the physics curriculum. To find out more and to RSVP for parking visit PhysicsAtTheBeach.com.

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Written by Laura Henriques

Laura Henriques is a professor of science education at CSU Long Beach and president-elect of CSTA.