Stimulating Predictions

Students correct misperceptions by predicting, testing, and observing results

Dale Johannson teaches science at an urban middle school with many students who are not native English speakers, and whose English fluency and reading skills range widely. Johannson has stopped relying on the science textbook to introduce his curriculum. Instead, he uses hands-on experiences to increase understanding, and his students benefit by the interactions, where they must use new science vocabulary.

Johannson started the year by introducing his physical science students to the concept of force. He set up a scenario he uses every year as a pre-test: A large, heavy car and a small, lightweight car were traveling down the freeway. Both cars hit head on into a sideways semi-truck. Johannson asked the students to predict which car would hit with greater force. His students overwhelmingly predicted that the larger, heavier car would hit harder, with more force. They failed to ask about other variables, such as the speed each car was traveling. When he revealed that the smaller car hit with greater force, the students didn't believe him. As he introduced Newton's laws of motion, he knew memorizing the laws would not establish a solid basis of understanding. Throughout the year his students conducted many hands-on experiments. This year, for the first time, the car crash could be "experienced and tested." The school's computer lab had just been connected to the Internet, and he had discovered an online simulation of that scenario.

Implementing Research-Based Strategies

• An interactive approach to teaching physics concepts provides a better environment for student learning than traditional textbook-based instruction (Hake, 1998).
• When students predict, test, observe, and compare, they model the scientific method. By generating and testing a hypothesis, they are also applying their conceptual understanding (Marzano, Pickering, & Pollock, 2001).

With his diverse class of learners, Johannson frequently uses generating and testing hypotheses as an assessment strategy. It allows the students to apply what they know, and he is better able to see their thinking in action.

• Understanding increases when students are asked to explain the scientific principles they are working from and the hypotheses they generate from these principles (Lavoie, 1999; Lavoie & Good, 1988; Lawson, 1988).

After students have time to explore and experiment, he asks teams to make a prediction about a variable and then run a test for him to observe. These predictions are good indicators of student understanding.

He encourages students to explain their hypotheses in detail. He also asks them to analyze their test results, encouraging self-assessment and reflection: Was their prediction accurate? Why or why not?

Technology Supporting Success

Computer simulations allow students to practice making predictions and testing for results. They can adjust variables and retest multiple times without having to set up a new physical experiment for each trial. If they are just learning a scientific concept, they can use a "guess and check" strategy to test their understanding. Simulation environments encourage exploration by allowing learners to manipulate their learning experience and visualize results.

In the computer lab, Johannson had students go to a Web site that features a simulation on roller coasters called Funderstanding Roller Coaster, which features a set of variables to control: slope, height, speed, mass, gravity, and friction. The user adjusts the variables and then runs a test. If the variables are predicted well, the car will make it from start to finish.

• Students gain in understanding when they are asked to explain the scientific principles they are working from and the hypotheses they generate from these principles (Lavoie, 1999; Lavoie & Good, 1988; Lawson, 1988).

Johannson told students to keep track of their results for each test and look for patterns. He asked them to run the simulation again, this time isolating only one variable in a series of tests. This opened a discussion about test design and controls.

The free Web-based simulation is easy to use and takes little explanation. That means Johannson can spend his class time questioning students about their predictions and outcomes rather than assisting them with laboratory equipment.

By the time Johannson's students finished their simulation, they had changed their initial misunderstandings about force and added new understanding of acceleration and friction. He was able to make a quick formative assessment that assured him students had learned the content he was trying to teach.

Simulation software enabled students to practice making predictions and testing outcomes. It also helped them improve their test design by allowing them to isolate variables. By combining practice with discussions, students were prompted to think through their understanding and raise new questions.