# Day 157: Refraction & Empirical Formula Lab

Physics: Refraction

Students played with PhET’s Bending Light simulation to start building some ideas about refraction. I tried to keep the questions very broad and focused on conceptual understandings. Students really took advantage of all the tools available and made a lot of very detailed observations that would have been tough or impossible in a more traditional lab.

Chemistry: Empirical Formula Lab

Students worked on a lab that terrifies me (I once had a careless student singe his eyebrows), but gives really nice results. Students started with a sample of copper II oxide, then burned off the oxygen to get pure copper. They then used their initial and final mass to determine how much oxygen was in the original sample and find an empirical formula.

So much fire!

# Day 156: Mistakes Game & Speed Dating

Physics: Mistakes Game

We played the mistakes game with ray diagrams for curved mirrors. Its been a while since we last did that, and a lot of students were excited to play.

Chemistry: Speed Dating

We did some whiteboard speed dating with empirical formula problems. By the end of the hour, most students were feeling pretty confident. Just to solidify that confidence, we did a “practice pop quiz” where I put up a problem and had students work through it in quiz-like conditions, then went through the answer and had some conversation about the next steps for people who didn’t do well on that quiz.

# Day 155: Ray Diagrams & Empirical Formulas

Physics: Ray Diagrams

Students took their first stab at drawing ray diagrams for curved mirrors. A lot of students made liberal use of colored pencils to keep the different rays straight.

Chemistry: Empirical Formulas

I introduced students to empirical formulas, focusing on them as a new layer to the percent composition work we started on Friday. Students were pretty successful with the new skill.

# Day 154: Curved Mirror Equation & Percent Composition

Physics: Curved Mirror Equation

Students collected a little more data from yesterday’s lab, then whiteboarded the results to get to the curved mirror equation. The graphs were not as consistent as with some labs, but students were still able to get where I wanted them to.

Chemistry: Percent Composition

Last trimester, a lot of my students struggled what they knew about percents from their math classes to percent composition in chemistry. This tri, before giving any instruction, I asked students to  answer a few questions like “What percent of this class is male?” Giving students those questions, then asking them to talk about the process they used, got students to bring the math into the class themselves, which lead students to make sense of percent composition much more easily than last trimester.

# Day 97: Speed Dating

Physics: Circuits Speed Dating

We did some whiteboard speed dating for compound circuit problems. I put different problems at different tables and, compared to when I’ve done all groups working on the same problem, it seemed like students were more willing to try and make sense of what their peers did. One of my favorite side effects is as students get frustrated trying to follow what a classmate did, they get more careful about showing their own work clearly. By the end of the hour, students seemed much more confident with these problems.

Chemistry: Empirical Formulas Speed Dating

This class also did whiteboard speed dating, but with empirical formulas. In my physics classes, the students who are struggling with a concept try to take advantage of this activity by asking a lot of questions when they’re with someone who has it down and working through at a comfortable pace when they’re with someone else who is struggling, which contributes to the value of the activity. In my chemistry class, I saw something very different. When my students struggling with the topic were with a stronger student, they tended to mostly watch what their partner was writing without much interaction or conversation. When they were with another student struggling with the material, both would seem to shut down and wait for the next rotation. I need to keep working with students on what effective collaboration looks like and how their actions in class day-to-day contribute (or not) to their performance on assessments.

# Day 96: Compound Circuits & Empirical Formulas

Physics: Compound Circuits

Students continued to work on yesterday’s compound circuit problems. A few students yesterday traced different paths through the circuits using colored arrows to provide a visual cue for which currents should add up, and a lot of students today found it helpful to add that representation. I was really pleased when a student insisted that the last problem, with the most complicated circuit, was the easiest in the set.

Chemistry: Empirical Formulas

Students finished up the lab from yesterday, then worked on some written problems finding empirical formulas. I didn’t take the time to discuss the connections between what the lab represented and what they were doing in the problems, and many students struggled to not only transfer ideas from the lab, but to bring back skills like converting mass to moles. I need to make sure I take the time to help students build those connections.

# Day 95: Compound Circuits & Empirical Formulas

Physics: Compound Circuits

Students worked on applying Kirchoff’s Voltage Law and Kirchoff’s Current Law to solve compound circuits. A lot of students made use of my colored pencil’s and of Trevor Register’s KVL diagram to help set up their equations. During the labs last week, I had a lot of groups come up with patterns based on ratios (i.e. every resistor in series has the same ratio of potential difference to resistance), but very few students set up ratios in the problems. I found that a lot of groups needed some prompting to think about how the labs last week relate to today’s problems. Next year, I may try doing some compound circuits in the lab or PhET circuit kit as a bridge to pure paper and pencil problems.

Chemistry: Empirical Formulas

Students found empirical formulas for samples of colored beads, where each color represents a different element. My goal was to give a concrete analogy for what is happening in the lab when they find an empirical formula.

# Day 94: TIPERs & Percent Composition

Physics: TIPERs

I introduced students to Trevor Register’s diagram for Kirchoff’s Voltage Law, then turned them lose on some questions from TIPERs that we used for the mistakes game. A lot of groups made good use of the KVL diagrams both in their groups and during the whole class discussion. We haven’t done the mistakes game much this trimester, but groups did a nice job of using their initial errors as a basis for their mistake.

Using the KVL diagram

Chemistry: Percent Composition

Students did a lab to find what percentage of a stick of gum is sugar. This is one of the first quantitative labs we’ve done, and students struggled with a question about likely sources of error in their measurements, so that will take some conversation on Monday.