Great Introduction for Physical/Chemical Changes and Balancing

What am I doing to help kids achieve?

How do I know when they are there?

What is the evidence?

I hate to sound like a broken record but I used two activities from that worked amazingly well and had a great "flow". Chad Bridle wrote two inquiry activities that dovetail together. The first is "Changes You Can Believe In". Students are presented first with nine cards that are particulate drawings of changes that occur in matter. Some are physical and some are chemical. After each group decides if they are physical, chemical, or both, they are then provided a "key" that explains the chemicals represented in each drawing. Finally, students asked to associate it with a third set of descriptions which explains the "real world" connection. The lab flows smoothly, challenges students thinking on physical and chemical changes and draws together the particulate and the macro scale. The next activity, "The Only Thing Constant is Change" uses the same cards. The great part about this lab is that now students actually examine the nine experiments in the lab. This brings the hands on macroscale to the forefront and builds on the particulate models they have used. It also introduces the symbolic balanced equations for each experiment. It works well in groups, provides experiments and questions for quick discussions and continuously scaffolds models, experiments and balanced equations. Even though students had not had much experience with the balanced equations, they quickly associated the symbols of reactants and products with they experiments and drawings. I would highly recomend these two activities.

Assessment for each of these can be a challenge. Students are tired at this point and some are preparing for high stakes tests. Both labs are great but can be a bear to grade. I have decided to do two things....first I am going to put an emphasis on the "Teacher Checkpoints". Second, I am going to do a "group quiz". It consists of five reactions as demonstrations. Each group will have to decide if they are viewing a chemical change, a physical change or both and provide evidence on either the macroscopic, particulate or symbolic level. I do not give group quizes often but I have found that I can ask questions that are a little harder and that the real value from the experience is the discussions that students have when trying to decide the answers as well as the evidence that goes with it. I will let you know how it goes....

 

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NGSS

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds.

Summary:

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds. Use a model to predict the relationships between systems or between components of a system.

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Comments 2

Deanna Cullen's picture
Deanna Cullen | Thu, 02/25/2016 - 15:16

Hi Chad, I have used both of these labs for many years now. They are very well done and students engage in the activities. Since I am constantly walking around and checking in on groups, I don't feel the need to do more than just skim most of the lab assignment itself. I have them turn the activities in and I only grade a small section near the end of each. These are the parts they complete after we have concluded our classroom discussion. I then provide them with several situations. They need to draw the particulate level model and then explain if/why the change was chemical or physical.  I practice a few with them first. I may try a couple of live demos per your suggestion this time around. THANKS!

Kristina Harkins's picture
Kristina Harkins | Wed, 04/26/2017 - 13:31

My curriculum introduces students to physical and chemical changes at the beginning of the school year. However, students do not learn about chemical reactions until the spring. I am currently using the "Changes You Can Believe In" lesson not only to review physical and chemical changes but also to expand my students understanding to the particulate level. We recently spent weeks discussion intermolecular forces. The students seemed to struggle most with imaging the molecules and then picking apart their structures for clues as to which IMFs would be present and then applying that knowledge to the effect on physical properties of the molecules. I am hoping that this lesson will be a great bridge between IMFs and chemical reactions. Thank you for posting this article.