Chapter 8 - Constructivist Learning Cycle
Constructivist Learning Cycle Lesson Example 1: What can be learned from skull?
Overview
Students observe a variety of vertebrate skulls and attempt to identify the animal and what it eats. Concepts such as herbivore, omnivore, carnivore, nocturnal, diurnal and niche are introduced.Invitation Phase
The teacher shows the students two or three vertebrate skulls and asks the students to predict what they could learn about the animal's behavior by studying skulls. Students work in small groups for about five minutes and then report their ideas to the class. The teacher uses students' predictions as a starting point for instruction, and uses the students' ideas in a discussion introducing the next phase.Exploration Phase
Skulls are placed at ten numbered stations. Students work in small teams and "visit" each numbered station, or the skulls are passed to each team. The teacher explains that the teams should be challenged to make inferences, like paleontologists do, about the lifestyle and habitat of vertebrates by observing their skulls. The teacher provides each group with one copy of the following questions:
- What type of food does this animal eat, and what is the evidence for your inference?
- Is this animal active during the day, night, or both? What is the evidence?
- Is the animal a predator or a prey? Why?
Explanation Phase
After the student teams have gathered data on each skull, conduct a session in which you ask different teams to describe each skull. Conduct a discussion focusing on the differences among the skulls. Have students focus on the teeth, for instance. Write the words on the board they use to describe them. Use the teeth to suggest function. Introduce the terms herbivore, carnivore and omnivore. Ask the students to explain what these terms mean. You can clarify student concepts and misconceptions by explaining carefully, for example: "This animal has sharp teeth for tearing and no flat teeth for grinding. This implies that it eats only animals. An animal that eats other animals is called a carnivore."Taking Action
Provide opportunities for students to investigate a variety of bones in addition to skulls. What inferences can they make from the structure about their function?Constructivist Learning Cycle Example 2: What Caused the Water to Rise?
Overview
Students invert a cylinder over a candle burning in a pan of water. They notice that the flame soon goes out and water rises into the cylinder. They engage in discussions to explain their observations. They then test their explanations, which lead to new explanations and understanding of combustion, air pressure and scientific inquiry.Materials
Aluminum pie tins, birthday candles, matches, modeling clay, cylinders (open at one end), jars (of various shapes and sizes), syringes, rubber tubing.Invitation
The teacher begins the lesson by asking students to predict what they think would happen if a glass cylinder was put over a burning candle that was sitting upright in a pan of water. Students work in small teams to discuss their ideas with each other. The teacher then asks for group reports, and records the student's initial ideas on chart paper. The teacher explains that the class will investigate this problem, and later in the activity, return to evaluate their initial ideas.Exploration
Give each team a student hand out describing the inquiry procedure, as well as the materials listed above. Students should then be given the opportunity to explore the phenomenon by the following these procedures.
Instructions
1. Pour some water into the pan. Stand a candle in the pan using the clay for support.
2. Light the candle and put a cylinder, jar, or beaker over the candle so that it covers the candle and sits in the water.
3. What happened?
4. What questions are raised? Write them down.
5. What possible explanation can you suggest for what happened?
6. Repeat your experiment in a variety of ways to see if you can obtain similar or different results. Do your results support or contradict your ideas in #5? Explain.
After 30 minutes of experimenting, stop the students for a discussion of their results. Focus the students on the questions such as Why did the flame go out? and Why did the water rise? The most likely explanation (misconception) to the second question is that since the oxygen was "burned up" the water rose to replace the oxygen, which was lost.
Lead the students to realize that this hypothesis predicts that varying the number of burning candles will not affect the level of water rise. Four candles, for instance, would burn up the available oxygen faster and go out sooner than one candle, but they would not burn up more oxygen hence the water should rise to the same level.
Have students do the experiment. The results will show that the water level is affected by the number of candles (the more candles, the higher the water level). Their ideas have been contradicted. Explain that an "alternative explanation" is needed and ask the students to propose one. As students propose alternative ideas do not tell them if they are correct. For example, the "correct" explanation (the heated air escaped out the bottom) should not be revealed even if students suggest it. Ask students to think of ways to test their hypotheses. If they propose the heated air hypothesis, this should lead to the prediction that bubbles should be seen escaping from the bottom of the cylinder. As alternative hypotheses are suggested, have the students test the hypotheses and look for evidence to support predictions. If students do not suggest the "correct" explanation, suggest it yourself. You might say, "What do you think about this idea? The heat from the flame heats the air and forces it out the bottom of the cylinder." Encourage students to test your explanation rather than accepting as is.
Explanation
After students have collected data testing various hypotheses, you should introduce the scientific explanation again and introduce the term air pressure and a molecular model of gases, which assumes air to be composed of moving particles that have weight and can bounce into objects (such as water) and push them out of the way. Provide an opportunity for students to compare and contrast their initial ideas (recorded on the chart paper), with ideas they generated in the lab activity, as well proposals that you make. Are the students dissatisfied with their prior conceptions (their predictions recorded on chart paper); is the new idea intelligible to them; and is the new idea plausible and fruitful (in their eyes) for future pursuits?Taking Action
Provide a number of problem solving situations in which students have opportunities to apply air pressure and the molecular model of matter.
- Problem #1: Give students rubber tubing, a syringe, a beaker and a pan of water. Tell them to invert the beaker of water in the pan of water. Challenge them to find a way to fill the beaker with water in that position. (The students will try forcing water in, before discovering they must extract air from the beaker.
- Problem #2: Challenge the students to find a way to insert a peeled, hard boiled egg into a bottle with an opening that is smaller in diameter than the egg They cannot touch the egg after it is placed on the mouth of the jar. (After a small amount of water in the bottle has been heated, it is only necessary to place the smaller end of the egg over the opening of the bottle to form a seal. The egg will be forced into the bottle by the greater air pressure outside as the air cools inside.
- Problem #3: Pour a small amount of very hot water into a large (2 L) plastic soda bottle. Then screw the cap on tightly to form a seal. Place the bottle on a desk so that students can view it. The plastic bottle will begin to be crushed. Challenge the students to explain the result using the molecular model of gases and air pressure.
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Based on Anton E. Lawson, Michael R. Abraham, and John W. Renner, A Theory of Instruction, National Association for Research in Science Teaching, NARST Monograph, Number One, 1989, pp. 96-99.