Day 166: Random Presenter & Mistakes Game

Physics: Random Presenter

I had each lab group whiteboard and present their solution to one of the lab practical stations. I assigned which practical each group would present so I could make sure we saw all four stations. I also, when possible, tried to pick groups that used different approaches, like the two groups in the photo who had to find the mass of some washers using a known mass, a spring, a ruler, and a stopwatch. In one of my classes, I tried rolling a dice to decide who would talk on behalf of the group, and I saw some students who tend to let someone else in their group figure things out really engaging to make sure they knew enough to present if picked. I need to use this strategy more often.


Chemistry: Mistakes Game

Students worked on writing equations for nuclear reactions, then we played the mistakes game with some problems.


Day 165: Final Review & Isotopes

Physics: Final Review

Students continued working through the lab practicals to review for the final exam. Overall, I’m pretty happy with how the review has been doing, though a lot of groups were confused about what they were being asked to do on the standing waves practical. I need to revise the directions to make it clearer that they should calculate the length of the tube needed to resonate, then use the materials to test it.


Chemistry: Isotopes

Students used what they know about isotopes to determine how many pennies in a sealed container were made before 1982 vs. after. They struggled to make the connection between the lab and what we’ve done so far on isotopes, so I need to make some changes to help students better build that link.


Day 164: Senior Skip Day & Half Life Whiteboarding

Physics: Senior Skip Day

Today was the unofficial senior skip day, so I had less than a third of my students in class. I normally limit students to two reassessments per week, but gave students who were in class today an opportunity to do some additional reassessments. A few came to my class just to take advantage of that. A couple of students who were in school so they could play in a baseball game this weekend asked if they could work on the final review.

Chemistry: Half Life Whiteboarding

Only a few of my students in chemistry are seniors, so we continued as usual. Students finished the problems from yesterday and whiteboarded their solutions. I got some pushback from a few students who were very vocal about their opinion that if the seniors are gone, they shouldn’t have to work on chemistry. This may make the last week of school tough since seniors are dismissed a week early, so I need to start thinking about how I will keep my juniors motivated.


Day 163: Final Review & Half Life Data Analysis

Physics: Final Review

Students started reviewing for next week’s final exam. I put together a lab practical for each of the four major topics from this trimester, and groups can pick and chose which ones they complete.

  • Simple Harmonic Motion: Given a 50 g mass, spring, ruler, and stopwatch, find the mass of a set of washers.
  • Mechanical Waves: Predict what length an adjustable tube needs to be for a given tuning fork to resonate when (a) both ends are open and (b) one end is plugged.
  • Reflection: Given the placement of a laser pointer and a target, use at least three mirrors to direct the beam to the target.
  • Refraction: Determine the index of refraction of oil.

There was a lot of demand for the simple harmonic motion and mechanical waves practicals since those were the oldest content. I’d prepared three sets of equipment for each practical, and ended up putting together a few more simple harmonic motion sets during my largest class, especially since they just did the index of refraction task for water yesterday.


Chemistry: Half Life Data Analysis

Students graphed their half life data from yesterday, then we compared their results to their predictions and the class totals, including data from previous years. We had some good conversation about the role randomness plays in the lab and why its useful to have data that relies on thousands of pennies, rather than just the 100 students had.

half life class data

Day 162: Snell’s Law & Half Life

Physics: Snell’s Law

I got out the refraction dishes and showed students how to use them to find a refracted angle. Then, I asked them to get me a graph where the slope is the index of refraction of water. This is the first time I asked students to start with an equation (in this case, Snell’s law) and pick their axes to get a certain value as the slope, but they were pretty successful.


Chemistry: Half Life

Students measured the “decay” of pennies by shaking them up, then setting aside any that came up tails. Each group make a graph of pennies remaining vs. half lives and submitted their results via a Google Form so we could produce a graph of the class average. Tomorrow, we’ll use that to have some conversations about randomness.

Day 111: TIPERs & Half-Life

Physics: TIPERs

Students worked through some questions related to magnetic forces from TIPERs. I overheard a lot of good discussions, and students shifting their ideas as they went.


Chemistry: Half Life

We spent some time going over the results of yesterday’s lab, then students worked on some half-life problems. Based on conversations with my students, many were struggling to connect the definition of half-life to the process for solving problems. I need to rework the lab discussion for next time to try and help students really get what half-life means.

Day 110: Motors & Half Life

Physics: Electric Motors

Students built simple electric motors, then experimented with how they could change the behavior of the motor. They drew a lot of nice connections between their observations and the previous work we’ve done on wires in magnetic fields. I let students use power supplies, and the sparks that showed up at higher voltages were very popular.


A student took this photo that’s way cooler than anything I got

Chemistry: Half Life

Students simulated radioactive decay using M & M’s, with one side representing the parent isotope and other representing the daughter. To reinforce half-life is based on probabilities, rather than hard and fast rules, I wanted to have students compare several runs of this experiment. Each group did the experiment twice, then submitted their averages to a Google Form. Tomorrow, we’ll look at the class data to see how it compares to the results of individual groups.

Day 109: Wire Loops & Nuclear Reactions

Physics: Wire Loops

My plan was for students to experiment with interactions between two wire loops with currents running through them, but we were not able to get much to happen with two loops. Instead, we ended up using some YouTube videos of the experiment to make observations. Students did get good results observing interactions between the wire loops and a magnet. This lab did provide a nice opportunity to revisit a common misconception from last week’s quiz, where a lot of students struggled to identify how a charge at rest would respond to a magnetic field. We were able to use how a wire with no current running through it responded to revisit the idea that charges must be moving.


Chemistry: Nuclear Reactions

Students did some problems predicting the products of nuclear reactions. This year, I really emphasized applying a conceptual understanding of conservation of mass to balancing chemical reactions, and that provided a good foundation for nuclear reactions. Even though the elements involved were changing, students were nicely primed to think about these reactions in terms of conserving protons and neutrons instead of elements.

Day 108: Balances & Isotopes

Physics: What does a balance measure?

A couple of students turned in their work from yesterday to my sub, and I saw they pretty consistently interpreted the balance in the video as measuring mass rather than force. To help clear that up, I took a balance on the school elevator and recorded some video. We started by drawing some free-body diagrams, then connected those to changes in the reading on the balance to get at what the balance is really measuring. From there, students whiteboarded and shared their answers to yesterday’s activity.

Chemistry: Isotopic Pennies

To introduce the idea of isotopes, students got sealed jars with 10 pennies and had to determine how many of their pennies were made before 1982 without opening the jar.