Two students pour sugar grains into a glass of hot water. They make three observations.
Note: The numerical scores indicated in the scoring rubrics were for research purposes. Higher scores indicate higher quality argumentation. We encourage you to use a scoring scheme that matches your present goals for students. We cannot see the sugar anymore because ….
Pictures of the sugar and water particlesThis is a picture of the sugar and water particles before they were mixed together: Which of these pictures best represents the water and sugar particles after they have been thoroughly mixed together? Arrangement: A, B, C, or D
Two students discuss what they think happened to the sugar.Laura says I think the sugar is gone. Mary says I think the sugar is still there. After stirring, each student tasted the water. They both agree that the water tasted sweet. Laura, Mary, both, or neither The weight of the sugar, water, and glass before it was added to the water is the same as the weight of the mixture and the glass after it was stirred in. Laura, Mary, both, or neither Matter cannot be created or destroyed. Laura, Mary, both, or neither Sometimes a substance breaks into very small pieces when mixed with another substance. Laura, Mary, both, or neither Note: Parts D2, D3, and D4 were not scored. Laura, Mary, both, or neither
At the end of the class, Mary makes the following argument: Mary's argument The sugar is still there. The total mass stays the same. If the sugar disappeared, the mass would have changed. The evidence in Mary's argument is ….
Evidence:
Select A, B, C, or D is not as good because ….
Now that you have seen some evidence and other students’ ideas, let’s return to the original question. Two students pour sugar grains into a glass of hot water. Once the sugar is poured into the water, it is stirred. After stirring, the sugar can no longer be seen. We can't see the sugar any more because ….
|