As students enter the room they take out their Chromebooks and respond to the prompt:
What are some qualitative and quantitative observations about the corn plastic we made last week.
As the students respond to the prompt, I circulate through the room looking at their answers to ensure that they remember the difference between qualitative and quantitative observations.
Once the students have had a chance to write a response, I ask for volunteers to review the definitions of qualitative and quantitative. As a follow up, I provide the students with an observation and ask them to tell me if it is qualitative or quantitative. After having the students identify a couple of practice statements, I ask for volunteers to share their journal responses with the class. As the students share information, I make a master class description list on the board.
The class will decide if an observation should go in the qualitative or quantitative side of the chart. After the chart is complete, we review the observations and see if the students came up with any conflicting observations. These conflicting observations are addressed as the students determine explanations for differences. Students are more comfortable addressing conflicting observations and expressing agreement or disagreement if they are provided with a format to follow for accountable talk. Examples of accountable language stems that work well in this context include: “I agree with _____ because _____.”
“I agree with _____; but on the other hand, _____.
“I disagree with _____ because _____.”
“I’m not sure I agree with what _____ said because _____.”
I have the students open their making polymers lab on their Chromebooks and we review the information from part one of the lab. I then review the guidelines for completing part two of the lab experience, as some of the students may find the information a little confusing.
The students should be able to answer the first few questions of part two without looking at their notes, but they may refer back to their notes if necessary. When working on the experiment portion of part two, the students are to use the left over liquids from the lab practical. After a quick review of lab safety procedures, the students go into the lab where they don their safety equipment and begin their experiments. I also explain to the students that they will need to make new corn plastic because their plastic grew mold over the weekend. (Exploring the growth of the mold could be a whole lesson on its own, and we may revisit it during our biology unit!)
The students begin working on their lab activities while I circulate through the room. I ask the groups to explain what liquid they are using to test solubility. In this video, students are conducting solubility tests for the reactants of corn plastic.
I also ask them to think about how pH is related to the activity. For instance, I ask them if they think a liquid with a higher or lower pH will break down the corn plastic more quickly. I then ask them to justify their answer and, if possible, use a real life example. During this time I am also assessing the students' ability to think creatively, work cooperatively, and measure accurately, as is listed on the lab grading sheet.
Once the students have completed part two of the lab, they are able to begin working on part three. Part three of the lab is more conceptual than hands on at this point, since I want to know how well the students understand the concept of biodegrading. The students will design an experiment, but we will not carry it out yet. This will take place during a different lab.
Each part of this lesson requires that students plan and carry out scientific investigations (NGSS SP3). This lesson also addresses NGSS MS-PS1-2 as students examine the corn plastic before and after placing it in a solvent of their choice.
I end class with a whole group discussion of which liquids the students chose to use to try and dissolve their corn plastic. I then ask a different representative from each group to explain why they selected that liquid. I require that the students provide at least three reasons for their decision. I encourage the students to ask questions of their peers during this process as well as provide evidence for their decisions.