Physical and Chemical Changes - Flipped (Day 2)
Lesson 3 of 19
Objective: SWBAT identify physical and chemical changes based on a laboratory experiment.
As the students enter the room, they each receive a note card with one of the words or definitions from a previous lesson. I ask the students to think about the definition of the word they have or the word that fits with their definition. After providing them with time to think, I ask the students to find their partner. Once they think they have found their partner, the students bring their cards to me and I check their work. If they are correct, I give them a blank note card and ask them to write the word on one side and the definition with an accompanying picture on the other. If the students do not have the correct partner, I ask them questions to guide them toward finding the correct partner. This set of cards is a little more difficult for the students because the definitions are not word for word from their notes, which requires them to think more carefully about general definitions for the terms. Once all of the students have found their partners, I give them all two minutes to finish up making their new cards. Some of the students have difficulty thinking of a picture to draw to accompany their word. I ask them to think of something that they could draw to help their classmates better remember the definition. At the conclusion of the lesson, I place the cards on a metal ring as a set of flashcards that the students can check out and use during study hall to begin preparing for the test.
Prior to finishing up the lab experience from the previous day, I ask the students to discuss the safety rules that need to be followed in the lab. For instance, I ask them what safety equipment must be worn and why. The previous day I had a student break a test tube and spill the hydrochloric acid on his apron, so I review this scenario as an example of the importance of wearing lab aprons and wearing them in the appropriate manner. I also remind the students of where their materials are located for completing the lab. The students then take out their Chromebooks and head to the lab.
Once the students have their aprons and goggles on, they are able to begin working on the lab. Today they are working with saltwater, silver nitrate, and hydrochloric acid. While the students work, I move from table to table, completing a lab checklist about their work. I also ask students if a component of the lab is an example of a physical change or a chemical change. Once they provide their answer, I further prompt them by asking for evidence to support their answer. I frequently stop to question groups about their observations and ask them to explain what is happening as they work through an activity on the lab sheet. In explaining their observations to me, they are developing a deeper understanding of the material. In this video, I ask students to describe the reaction taking place between hydrochloric acid and magnesium ribbon.
This video demonstrates the reaction that occurs when silver nitrate is added to salt water.
The completion of this lab addresses NGSS - MS-PS1-2, which states that students should be able to analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
Once the students have finished the activity portion of the lesson, they clean up their lab areas and begin working on the accompanying questions. When there are five minutes left of class, I have the students log in to Socrative to complete a brief exit ticket in which they explain one type of change they observed in the lab, provide an example of the change, and evidence to support their answer.