I’m a hands on teacher. I want kids to do things instead of me telling them things. But if I’ve learned anything over the last few years, it’s that the power of science demonstrations is a pretty awesome thing.
Science Demonstrations Are Captivating
Think of the moments you crave as a teacher – where students are completely engaged. They can’t take their eyes off of what is going on. They have huge smiles on their faces and ask so many questions. I find myself in those moments most during demonstrations. I forget how captivating science can be!
Teachers are told that kids need to be doing the work and manipulating the materials. What is the point if they aren’t directly interacting with it? Turns out, there is a time and place for demonstrations.
Kids are uniquely engaged while a demonstration is taking place. They feel suspense and excitement. They’re so curious. It’s a feeling that is rarely matched.
Check out three of my favorite demonstrations!
First of all, did you know that red cabbage contains an enzyme that reacts with a substance to reveal its pH?? I didn’t either! Read about how to make it here if you’re interested, it’s a lot to explain!
This lab was a must. I wanted my seventh graders to grasp the concept of pH. However, buying enough supplies for eight group in each of my five classes was not an option.
So instead of giving up, I did a demonstration. The supplies were laid out on the counter. We tested apple juice, vinegar, shampoo, glass cleaner and a few other things. Students came up to measure, pour, and stir. Acids turned red and bases turned blue. The kids were so excited. The ooohhs and aaahhhs I heard as we measured and poured were the best! Definitely a win!
I knew this was not going to go over well if I let the kids do it. No. Way.
This demonstration super easy, but super cool! This is easy, because it doesn’t take a whole lot of time. The basic idea of convection is that hot material rises and cold material sinks.
Collect four small, identical jars or beakers. Fill two small jars with hot water and two small jars with cold water. Add some food coloring to the hot and cold water to differentiate between them.
Even middle school science students who have learned about convection think the two colors of water are going to mix in both demonstrations. Why wouldn’t it? Every other time they have added one color to another, they’ve mixed to create a new color.
By placing the jar of cold water on top of the jar of hot water, convection occurs and the two colors mix uniformly. Students watch the convection currents mix the water and are completely captivated. They ALL want to know what is happening.
When you place the jar of hot water on top of the jar of cold water, convection doesn’t happen! The cool water is already at the bottom and the hot water is already at the top. The colors do not mix.
Students are completely mind blown. I hear about this demonstration in the hall for the rest of the day and at the next parent teacher conferences!
Half of their excitement was probably from me spilling water so many times, but oh well! I suggest using glass bottles if you try it! Plastic did not work so well.
Density of Gasses
This one is fun!
Carbon dioxide is more dense than air. But that means nothing to the student sitting in your class. If anything, it is going to be a fact they memorize with absolutely no understanding behind it. (PS… if you want to read about how to teach density, check this blog post out!)
Create CO2 Gas
First, get a clear bucket with deep edges and fill the bottom with water about an inch or so high. Drop some dry ice in the bottom. (Do not touch the dry ice with your bare hands! Remember your lab safety skills!)
Next, let this settle a little bit. The process where it goes from a solid directly to carbon dioxide gas is called sublimation.
(If you can’t or don’t want to deal with dry ice, put a layer of baking soda in the bottom and pour vinegar in it. The chemical reaction creates carbon dioxide gas. Just let the bubbles settle down before you continue with the next part.)
You have a few options here. One, bubbles. Two, fire.
Blow bubbles into the classroom. Students will notice that they sink to the ground. Next, blow bubbles into the bucket. They don’t float all the way down. The reason? They’re filled with air. Air is less dense than carbon dioxide. And while students can’t see the CO2 gas, it’s there keeping the bubble from landing in the water.
Light three small candles. Your students should know that fire needs oxygen to burn. Grab a pitcher and scoop some air out of the bucket. Not the liquid at the bottom the CO2. You’re students will look at you like you’re crazy!
When you ask them what’s in the pitcher, they’ll likely say nothing or air. Actually, carbon dioxide gas is in the pitcher. Slowly pour it over the flame.
The candles will burn out. Why? The CO2 gas is more dense than air and stays in the pitcher until you pour it out. Student’s can’t see this because, well, it’s a gas. But they can see the evidence of the gas when the flame goes out.
Make It Even Better
If you’re up for it, find a paper towel roll, cut it in half long-ways and tape the ends together. You’ll have a long half pipe shape. Do the same demonstration, but prop one end of the paper towel roll up on a stack of books.
Light the candles, be careful, and place in a horizontal row with the paper towel roll, but not too close. When you pour the CO2 at the top of the ramp, the candles will go out one at a time.
This demonstration is so exciting! Chances are, they’ve never seen something like it. Best of all, it illustrates a concept that is so hard for students to grasp!
Let Them Participate
Engage them. Let them pour, or cut, or measure. Ask questions. Have a conversation with them as you are presenting your demonstration. This is what makes science come alive to your students!
It is totally possible to be engaging, exciting, and authentic without handing the reins completely over to your students. Every day is different. Every topic is different. Use your judgement on when to do a lab or a demonstration.
Tell me your favorite science demonstrations in the comment section! I want to know what you use in your classroom!