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Asia-Pacific
Forum on Science Learning and Teaching, Volume 6, Issue 2, Article
6 (Dec., 2005) Muammer CALIK and Alipasa AYAS An analogy activity for incorporating students' conceptions of types of solutions
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Asia-Pacific
Forum on Science Learning and Teaching, Volume 6, Issue 2, Article
6 (Dec., 2005) Muammer CALIK and Alipasa AYAS An analogy activity for incorporating students' conceptions of types of solutions
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Focusing on the target concept
In this phase, students debate the bus analogy in small groups to evaluate their pre-existing ideas. We first represent students' conceptions and then describe how the analogy includes students' conceptions.
1. Many students thought a solution in equilibrium with undissolved solute was a supersaturated solution (Pinarbasi & Canpolat, 2003). Since students are able to visualize the bus analogy, they may acquire the idea that if enough solute is available, a supersaturated solution is prepared by heating and then by cooling the solution. Therefore, they may grasp that to form a solution the solute must disperse into solvent rather than staying at the bottom as undissolved solute.
2. Seeing undissolved solute as a component of solution forms the idea that a supersaturated solution includes the undissolved solute (Pinarbasi & Canpolat, 2003). Since women and men sit down the seats of bus homogenously, they may improve the idea that preparing a supersaturated solution not only need to be heated if enough solute is available, but also be cooled. Also, they may comprehend that to produce a solution must incorporate in dissolved solute rather than undissolved one.
3. Some of the students at lower grades tended to exploit some hypothesis such as if solution in Beaker B is a saturated solution, solution in Beaker A must be an unsaturated solution (Calik & Ayas, 2005a). The analogy not only indicates criteria of saturated solution as 100 ml solvent but also shows that dilute or concentrate solutions does not include a constant criteria. In case of the dilute and concentrate solutions, the principal difference is the amount of solute at the same solvent.
4. Some of the grade 7, grade 8 and grade 10 students stated that both of the solutions are the same because, both of them include sugar (Calik & Ayas, 2005a). Analogy points out that there are differences amongst types of solutions, i.e., changing the numbers of women in each of the bus stops at the constant number of men is similar to that of solute at the constant amount of solvent.
Teacher clarifies incomprehensible points of the analogy, but refrains from providing any clues so that she/he allows students to implement interpretive discussion while carrying out it. During the discussion, students are asked to answer to the following questions: "each of four beakers includes 100 ml water at the same temperature. Three of them incorporate table salt, but the other one does not. 15 g table salt is dropped into water in Beaker B whereas 36 g table salt is added into each of Beaker C and D. Then, a bit of table salt is put into Beaker D, and then, it is heated until the new added solute dissolves. Thereon, Beaker D is cooled to its onset temperature (at the room temperature solubility of table salt is 36 g/100 ml). Which of the foregoing situations is similar to context of this case? Explain your reason?", "if you think men as solute and women as solvent, which of the foregoing situations reflect the terms "supersaturated solution, saturated solution and unsaturated solution" Explain your reason", "each of two beakers contains 50 ml water at room temperature. Latter, 5 g table salt is added into one of the beakers, whilst 10 g table salt is also dropped into the remaining one. Which of the foregoing situations is similar to context of this case? Explain your reason", "Could you match the terms "dilute and concentrate solutions" with the given analogy? Explain your reason", "Is a saturated solution equivalent to a concentrate solution? Explain your reason?" "Is an unsaturated solution equivalent to a dilute solution? Explain your reason?" "While you are matching the terms "dilute and concentrate solution", why solubility of table salt at 100 ml water is not given? Explain your reason?"
After answering the questions about the analogy, in order to determine whether or not students have understood the types of solutions, they are asked to respond the subsequent question: "Based on your answers to the questions, explain the distinctions between the terms "dilute-concentrate solutions"and "unsaturated-saturated-supersaturated solution" and what each of the terms means."
Copyright (C) 2005 HKIEd APFSLT. Volume 6, Issue 2, Article 6 (Dec., 2005). All Rights Reserved.
