Science.1.8.B
The student is expected to
describe how some changes caused by heat may be reversed such as melting butter and other changes cannot be reversed such as cooking an egg or baking a cake.
Knowledge and Skills Statement
Force, motion, and energy. The student knows that energy is everywhere and can be observed in everyday life.
Demonstrated Proficiency
Present the statements below to the students. Ask students whether they agree or disagree with each statement. They must add an explanation for why they agree or disagree.
"Melting a chocolate bar can be reversed." agree/disagree why?
"Cooking an egg can be reversed." agree/disagree why?
"Baking bread can be reversed." agree/disagree why?
"Melted candle wax can be reversed." agree/disagree why?
As students explain why they agree or disagree, look for evidence that they understand that some, but not all, changes are permanent. They may explain that they know a melted candle can be reversed because they've watched a candle cool down and become solid again. They may explain that they know a cooked egg cannot be reversed because there is nothing that can be done to make it raw again. Grade 1 students are not expected to discuss chemical properties or changes. Their explanations will be based on experience and discussion of observations they have made.
Further Explanation
As an educator, it is helpful to know that a common misconception is that all physical changes are reversible changes and all irreversible changes are chemical changes. This is not the case. An example of a physical change that is irreversible is when a rock is broken into pieces. A chemical change that is reversible is when a depleted rechargeable battery is charged. In grade 1, students are only expected to discuss whether or not changes are reversible. They are not expected to discuss the underlying physical or chemical change that occurs.
Supporting Information
Research
Lott, Kimberly, and Anitra Jensen. “Changes Matter!” Science and Children 50, no. 2 (2012): 54–61. http://www.jstor.org/stable/43176255.
Summary: There are several common misconceptions addressed in this article that elementary students have about physical and chemical changes and whether or not these changes can be reversed. These misconceptions can stick with students as they progress into upper-grade levels. Students should understand that heat can cause both physical and chemical changes and that some changes caused by heat can be reversed and some cannot.