No one cared that it was cold outside. These kids could hardly wait to see what would happen next. Giggles and laughter bounced from child to child as the group of second graders positioned themselves around the 2-liter bottle of diet soda.
In a whispered voice, one boy asked, “Do you really think she’s going to do it?”
“Sure… she’ll do it, but you have to get ready to run,” replied the girl standing next to him.
Mrs. Schmidt removed the roll of Mentos mints from her pocket and loaded them into a small tube that attached to the top of the soda bottle. The only thing that kept the Mentos from falling into the soda was a plastic pin tied to a piece of string.
“Are you ready?” Mrs. Schmidt asked.
“YES!” shouted the students who could hardly contain themselves.
“Three… Two… One… Go!”
It all happened in a fraction of a second. Mrs. Schmidt pulled the string, the Mentos fell into the soda and a giant soda geyser shot up everywhere. It was raining Diet Coke! As soon as the soda started to spray, the children scattered.
The students screamed, “That was awesome… do it again!”
When Mrs. Schmidt finally regained control, she told the children, “This is just a ‘one-time’ experiment. I don’t have any more soda, but wasn’t that cool?”
As she walked her students back into the classroom, Mrs. Schmidt knew that she had hit a home run with her exploding soda experiment. It had all of the elements of a great science lesson… it was hands-on and the fun factor was huge.
Okay, But Where’s the Science?
Like many primary teachers, Mrs. Schmidt thought that she had presented a great science lesson with her soda geyser activity. In her mind, she was doing an exciting, hands-on activity and her students were having a blast. However, if you look at the activity on a deeper learning level, you’ll start to uncover the most important missing element… the act of actually doing science! The harsh reality is that Mrs. Schmidt’s flying soda activity was cool, but her students were never doing science. The only level of student engagement was running away from the flying soda. The bottom line is that the students watched their teacher perform a cool trick using mints and soda, but calling that science is wrong on many levels.
Missing Elements… Wonder, Discovery and Exploration
The first key to engaging students in doing real science is to understand the difference between a science demonstration and a hands-on science experiment. Demonstrations are usually performed by the teacher and typically illustrate a science concept. Science experiments, on the other hand, give participants the opportunity to pose their own “what if…?” questions, which inevitably lead to controlling a variable – changing some aspect of the procedure or the materials used to perform the experiment.
In Mrs. Schmidt’s case, the students were never given the opportunity to ask questions, make changes, create a hypothesis or compare the results of the new experiment with the original. When the students yelled, “Do it again,” this should have been music to Mrs. Schmidt’s ears. The great Mentos Geyser experiment captured her students’ interest, and they were, in essence, begging for an opportunity to explore, to ask their own questions, to test changes to the procedure, to formulate new ideas and to make their own big discovery.
Instead, Mrs. Schmidt gave a commonly used response when her students wanted to be engaged – “No, this is a ‘one-time’ experiment.” One time? Who can eat just one potato chip? No one ever performs an experiment just once! Demonstrations may be one-time events, but great experiments lead to more questions, which lead to making changes and trying the experiment again. It’s a wonderful cycle of critical thinking called scientific inquiry… and you don’t need a PhD in rocket science to pull it off.
Great Demonstrations Lead to Greater Questions
One of the attributes of an amazing science teacher is to watch how he or she uses a cool science demonstration to grab the students’ attention and stimulate their natural curiosity. Great science teachers use demonstrations in such a way that they invariably precipitate the question, “How did you do that?” There is evidence to show that students retain science concepts much longer when they are shown an engaging demonstration that provokes an inquisitive response and that challenges them to figure out why. If the science demonstration served its intended purpose, the students will come alive with a stream of questions, and it’s the job of a great teacher to help the young scientists turn their questions into an unforgettable learning experience.
Gather Up the Soda and Mentos – Let’s Do Some Real Science
The only way to better your skills as a teacher is to test out these techniques with your students. Mrs. Schmidt started out with a fantastic science demonstration showing how the pits on the surface of the Mentos helped to pull the carbon dioxide gas out of the soda. The giant geyser had more than enough wow factor to pique her students’ curiosity and to provoke a handful of “what if…?” questions.
Listen to the Questions
This first step is crucial to creating a student-centered experience. The students need to take ownership of their questions and have a vested interest in finding an answer. Depending on the age of the students, you might need to ask a probing question like, “If we did this again, what would you like to do differently and what do you think would happen?” Encourage the children to work in small groups to come up with their questions. Some of the common questions might include…
1. What would happen if we used only one Mentos mint? What if we used the whole roll of Mentos?
2. Does it work with other kinds of soda? What about other kinds of candy?
3. What would happen if we shake the soda?
Each question could turn into a long list of experiments, so it’s important to talk about each question in an effort to narrow down the choices and help the students focus on one main question. Otherwise, you’ll spend a small fortune in diet soda and chewy mints.
Use the Scientific Method
Hypothesis – Let’s start with your hypothesis. After considering all of the questions, let’s say you want to find out if one Mentos mint works as well as seven mints. Think of your hypothesis as just your starting place. There will be plenty of follow-up questions as you conduct more and more tests, but you want to make sure that you answer your hypothesis at the very end of your project.
Materials – Now you’ll need to get your materials – soda and Mentos. You will need to purchase seven, 2-liter bottles of soda, making sure that the brand is the same. Here’s a helpful hint – use diet soda – it’s not sticky!
The Experiment – Since the number of Mentos is the variable, you’ll want to make sure that everything else in the equation stays the same. This is called the fairness test, and once children see the principle in action, they will put it to good use. Make sure all of the bottles of soda are kept in the same place (cold soda might erupt differently than warm soda!). Use the same method for dropping the Mentos into the soda.
Gather Data – You’ll need to find a way to measure how high the soda geyser shoots up into the air. One method is to find a tall, brick building and to use one of the walls as your testing site. Set the bottles of soda next to the brick wall and drop in the Mentos. It’s easy to count the wet bricks and to use this scale as a way of recording the height of each geyser. For example, let’s say the test using two Mentos made the soda shoot up thirteen bricks while the test using three Mentos reached sixteen bricks. This is a simple way to establish a scale… and the diet soda washes off easily.
Make Discoveries – The data you gather during the experiment should ultimately lead you to an “ah-ha” moment. Consider this a mini discovery. It’s not your conclusion, but rather a small discovery that prompts you to ask, “Based on what I just discovered, here’s what I would change if I did the experiment a second time.” A good rule of thumb is that a science project should have at least three mini discoveries upon which the experimenter can base a conclusion. It’s hard to arrive at a meaningful conclusion based on a single experiment. Real scientists conduct multiple experiments to help them accurately arrive at their final conclusion.
Conclusion – You’ll find that some students enjoy looking at the data as much as performing the experiment. In the example of the bottles of soda, the students will have seven pieces of data to examine. Using a bar graph, it’s a simple matter of charting the results and answering the students’ initial question – Does the number of Mentos make a difference? (I’ll let you figure out the answer on your own!) The final tip is to let the students do the talking as they interpret results. Let each student share his or her own discovery and work with them to arrive at their big discovery, based on real data and real science.
Beyond the Fizz
No one can ever fault Mrs. Schmidt for sharing the Mentos Geyser with her students. If her primary goal was to get her students excited about science, she did it – but hopefully she discovered a much more valuable treasure when she gave her students the opportunity to engage in the learning process. In the hands of a great teacher, cool science demonstrations like the Mentos Geyser open the door to an amazing journey filled with wonder, discovery and exploration. By using the power of inquiry to create unforgettable learning experiences, you rekindle a child-like sense of wonder—in both your students and yourself —right before you turn them into a soaking mess from flying soda. Don’t worry… they’ll be talking about it at the dinner table for years to come.