In the previous lesson, students were introduced to the characteristics of charged particles, so our goal today is to apply that knowledge in a static electricity lab activity (SP3 & SP8). Specifically, students use friction to charge tape strips and make observations about their interactions (HS-PS1-3). I start the class with a 1-minute essay introduction, then we move into the lab activity before doing a hand signal closure.
This lab requires a the following materials: straws, tape, and Styrofoam. Prior to students arriving, I have a complete set of these materials at each lab station around the room.
To start class today, students come into the room and take out a blank sheet of notebook paper. On the board I've written "How can you determine if an object is positively charged, negatively charged, or neutral?"
This is a 1 minute essay activity, where students get only 1 minute to answer the question and must work individually. The goal is to get students thinking about what they already know before they even start the static lab. I use a stopwatch, but because some of my students need a little time to process I usually give them about 90 seconds.
After their time is complete, I ask for volunteers to share their essays. I try to be a facilitator during this process and let students consider the responses of their peers. For example, if a student makes an assumption that is not valid I let another student speak up and question the invalid statement. I also encourage students to write down any valid ideas that they had forgotten to include.
The goal of this strategy is to remind students that opposites attract and likes repel (in terms of charged objects). I'm also hoping that students reference the methods of charging that we discussed yesterday. Once these concepts are shared in an essay, I emphasize their importance and move into the lab activity. Students keep their mini-essays as a reference for the lab.
Students get to choose their partners for this lab since it will need to be completed outside of class time and I want to make sure they are comfortable contacting the people in their group. I suggest that students work in groups of two, although I allow students to work alone or groups of three if they are more comfortable. One person from each group comes to get the materials and a copy of the lab.
The lab starts with students tearing paper into small pieces and observing interactions between the paper, a straw, and Styrofoam. Then, students use strips of tape and observe interactions with the pieces of paper and other strips of tape. Throughout the lab, students modify a given definition of "electrically charged" based on their observations. They also design several mini-experiments and draw conclusions based on their observations.
Even though the lab directions are clearly written, I make sure to circulate throughout the room and check-in with each of the groups. I offer students feedback on their conclusions and ask probing questions such as "How do you know that's charged and not electrically neutral?" When there is approximately 10 minutes prior to the end of class (5 minutes left of the time I've allowed for this lab), I ask students to put everything back the way they found it and return to their seats. I also tell them at this point that the lab will be due one week from today.
This lab sample is a nice example of what I hope students are able to accomplish. This group clearly answers the questions in complete sentences and includes a purpose, procedure, and conclusion for each mini-experiment. From their writing, I can tell that this group of students has a good grasp on charge interactions and is ready to move forward in this electrostatics and electricity unit.
To assess how my students are feeling about the properties of electric charges, I ask students to show me hand signals. Before I share the prompt, I show students their 3 options: a thumbs-up for agreement, a thumbs-down for disagreement, and a flat hand for uncertainty.
Once the students are ready, I say "I understand how objects attract, repel, or remain neutral when interacting with other objects." I then pause and repeat the prompt before asking students to share their hand signals, so that they have a moment to fully embrace and think about how they are feeling. The atmosphere is mostly quiet during this closure so that students are individually assessing their own level of understanding.
As students show their hand signals, I make a mental note of how many students are showing a flat hand or thumbs-down. There were no students that showed thrumbs-down, so this tells me that my instruction during the previous class and the lab activity today were effective learning tools for my students. As a teacher, all positive feedback tells me that I can feel confident in my students' abilities and move on to the next part of this electrostatics and electricity unit.