GENERATING AND TESTING HYPOTHESIS

 By: Dr. Armãndo R. Tolliver | EDUCATOR | March 24, 2017

Science teachers are well acquainted with inquiry as integral to the understanding of science. These processes require students to wonder “why,” ask questions, generate and test hypothesis, and seek answers to those questions. This is the nature of inquiry. “Inquiry engages students with their own thinking processes. It teaches students to think for themselves instead of chasing the right answer” (Allen, Kimura-Walsh, & Griffin, 2009, p. 305). When students generate and test hypotheses, they are engaging in complex mental processes, applying content knowledge like facts and vocabulary, and enhancing their overall understanding of the content (Varlas, 2002; Donohue & Gill, 2009; Marzano, Pickering, & Pollock, 2006; Kuhn, Hubbell, & Pitler, 2012). Researchers have indicated that students who generate and test hypotheses by engaging in problem solving have a clearer understanding of lesson concepts (Kuhn et al., 2012; Marzano et al., 2006).

            One of the great tools I use in the classroom to help foster questioning, hypothesis development, and data analysis is demonstration of discrepant events. The discrepant event’s surprising, often counterintuitive outcome creates sort of a cognitive disequilibrium that temporarily throws students mentally off-balance. For example, common sense tells us balloons and flames do not mix, but during one in-class demonstration students observed a balloon over a candle flame without bursting the balloon. The unexpected outcome of such a discrepant event generated a need-to-know that motivated students to thoughtfully reconsider their prior conceptions and generate new hypothesis.

            Here is what happened. I opened an introductory lesson with a definition of the term hypothesis. I had students list characteristics of a high-quality hypothesis, and asked a few students to share their ideas for expectations of a quality hypothesis. Some of the responses included “Mention of independent and dependent variables” and “Explain what one variable will do to the other variable.” Next, I distributed a Developing a Testable Hypothesis handout to students in order to discuss the difference between a prediction and a hypothesis and how initially writing a predication can inform the writing of the hypothesis. We then proceeded to the demonstration.

To conduct the demonstration, I blew up a balloon, just as you normally would, and tied it off, before lighting a candle and placing it in the middle of the demonstration table. I asked students to make a prediction as to what they thought would happen if I placed the balloon over the candle flame. Afterwards, I had the students turn their predictions into a hypothesis. The students shared some of their hypotheses aloud, “If the balloon is held over the flame, then the flame will cause the balloon to expand and burst.” It was time to test things out. I held the balloon a foot over the top of the flame and slowly moved the balloon closer and closer to the flame until it popped. The students noticed that the flame does not have to even touch the balloon before the heat melts the latex and the balloon pops. Let’s just say I had to prove what we already knew.

I then repeated the experiment, but this time I filled the bottom of the balloon with a layer of water inside. I asked the students to make a hypothesis about what would happen and why. I held the water-filled balloon at the top while I slowly lowered it over the candle. The students began running. I stopped for a second and asked the students to share their hypotheses. One student said, “It is not going to pop, I know it.” I then, picked up the candle in one hand with the water-filled balloon in the other and stood in a chair. I invited the student who made the statement be a volunteer and stand under it. The student unsure of his hypothesis, reluctantly came up. I eased his uncertainty by giving him an umbrella, just in case. Again, I held the water-filled balloon at the top while I slowly lowered it over the candle and watched as students started to run. Everyone, except one, just knew it was going to pop, but for some strange reason it did not. I even left the water-filled balloon in the flame for a few seconds and it still did not pop. The students began asking, “Why did that happen,” and began to show added interest. When I removed the balloon from the heat, I had the students carefully examine the soot on the bottom. Before going into the explanation, I had the students try to figure out why the layer of water kept the balloon from popping.

After the demonstration, I first had students create three questions, one for each of Costa’s Levels of Thinking. One student wrote:

1. Describe what happens when an empty balloon is held over a flame.
2. Compare the effects of a flame on an empty balloon versus a water-filled balloon.
3. Predict what would happen if the balloon was turned so that the candle flame is close to the side of the water balloon.

Subsequently, we held a whole-group discussion of the science behind the demo. Water is a great substance for soaking up heat. The thin latex balloon allows the heat to pass through very quickly and warm the water. As the water closest to the flame heats up, it begins to rise and cooler water replaces it at the bottom of the balloon. This cooler water then soaks up more heat and the process repeats itself. In fact, the exchange of water happens so often that it keeps the balloon from popping, until the heat of the flame is greater than the water’s ability to conduct heat away from the thin latex and the balloon pops. We took it a step farther, I asked the students to predict what would happen if the balloon was turned so that the candle flame is close to the side of the water balloon. A students provided an alternative hypothesis, “The balloon will pop because the water is not conducting the heat away from the surface of the balloon.” We tested this hypothesis. Needless to say, the water will helped put out the fire. Additionally, I explained to the students that the soot on the bottom of the balloon is actually carbon. The carbon was deposited on the balloon by the flame, and the balloon itself remained undamaged until we added the second variable (i.e. flame placement on the balloon).

We continued our discussion with real world application. I posed the question, “Is there a real life situation where this can be applied or used to work for other problems?” A few students shared their responses and we went into dialogue about how using water to control heat is a valuable process. Special superabsorbent polymer foams are currently being used by firefighters as a way to help protect homes from being consumed by a raging forest fire. The water-absorbing polymer foam is similar to the superabsorbent polymer found in a baby diaper. The foam is applied like shaving cream to the outside of the house. As the fire burns closer and closer to the home, the water-filled foam absorbs heat energy from the fire and buys firefighters some extra time as they try to fight the flames with water. Your body even uses water to control heat. When you exercise, your body produces sweat in an attempt to regulate your temperature so you do not get overheated. As the sweat evaporates, it takes heat energy with it, leaving cooler skin behind.

After the discussion, students were asked to create question cards that summarize concepts and address the Costa’s Levels of Thinking questions they created in order to reflect and review the information from the lesson. Also, students were asked to write a summary for the demonstration that had to use key terms discussed and address the purpose of the demonstration, science explanation of the demonstration, and an application of this phenomenon. The real difficulty in performing this effect is making it look harder than it is. Steve Spangler Science (2015) calls this demonstration the Fire Resistant Water Balloon. You can check out this demonstration here. In the future, I might consider trying to differentiate this lesson by providing this as a self-directed demonstration at lab stations, or as a small group activity for more homogenously grouped students.

Suggested Citation

Tolliver, A. R. (2017). Generating and Testing Hypothesis. [Education Project Online]. Retrieved online at http://www.educationprojectonline.com/2017/03/generating-and-testing-hypothesis.html.

References

Allen, W. R., Kimura-Walsh, E., & Griffin, K. A. (2009). Towards a brighter tomorrow: college barriers, hopes and plans of Black, Latino/a and Asian American students in California. Charlotte, NC: IAP, Information Age Pub.

Kuhn, M., Hubbell, E. R., & Pitler, H. (2012). Using Technology with Classroom Instruction That Works. Association for Supervision and Curriculum Development.

Marzano, R. J., Pickering. D. J, & Pollock, J. E. (2006). Classroom instruction that works: Research-based strategies for increasing student achievement. Alexandria, VA: ASCD.

Varlas, L. (2002). Getting acquainted with the essential nine. Alexandria, VA: ASCD Curriculum Update.