Physical & Chemical Changes

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Objective

SWBAT explain the difference between a physical change and chemical change.

Big Idea

Sometimes it's obvious, sometimes it's not. Learn to notice the signs of a physical or chemical change to become an expert.

Engage

10 minutes

Engage 

At this point in the year, students are familiar with the scientific method, so I chunk the lesson to let them work more independently. I ask students to read the question on the inquiry, read the background information, and then write an hypothesis on the Inquiry sheet. Doing this will engage students in the lesson and learning. I want students to work collaboratively with their peer group on the first three parts of the inquiry, so I provide about 10 minutes and then check back with the class. 

I circulate the classroom while students are working to assess their understanding. At this point, I can determine which students are ready to share their hypothesis with the class. Sharing aloud with the class is a good opportunity for students to hear other student's thinking.

Explore

25 minutes

Explore

I chunk the next part of the inquiry so that students can investigate, experiment, collect data and analyze information with their peers. I want students to be able to MS-PS1-2 analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. The inquiry allows me to assess if students understand  the difference between a chemical change and a physical change and can explain that by identifying signs of a change.

As students investigate the physical and chemical changes of matter, there are a variety of standards woven throughout the learning. Students (SP#1) ask questions during the inquiry. They (SP#2) develop and use a model (soda bottle with vinegar and baking soda) to explain how mater behaves in a chemical change. Students (SP#3) carry out an investigation as they perform the experiment to test their hypothesis. They (SP#4) analyze and interpret data collected in the data tables to recognize patterns and see relationships between different types of matter. Students (SP#6) construct an explanation about how to identify a physical change from a chemical change and then (SP#7) collaborate with their peers to search for the best explanation to their findings from the inquiry. Ultimately, students will (SP#8) accurately communicate their findings in order to engage in discourse with their peers. Math Practices are tied into the lesson as well. (MP#5) students use appropriate tools (triple beam balance) strategically and (MP#6) attend to precision as they accurately measure matter in each part of the inquiry.

Student Explaining Chemical Change

Evaluate

5 minutes

What did you learn?

I ask students to reflect on the target (objective) and explain the difference between a physical and chemical change.

As with any experiment, sometimes it works and sometimes it doesn't, but that ok. This provides opportunity to discuss what went right, what went wrong, and changes that could be made to the experiment. This step is very important for students to "come full circle."

I have learned that you need to take students back to the question so they can think about the process. How can I identify a physical change from a chemical change? Take 1-2 minutes for students to process this question and write a conclusion. I give them a sentence starter to help with the process, for example:  I learned that . . .because. . .  Take 1-2 minutes to share answers with the class so students can hear other student thoughts.