# Day 74: Balanced Force Practical & Field Lines

AP Physics: Balanced Forces Practical

I tasked students with figuring out the unknown masses in a set up with several strings at different angles. Groups found they had to be very clear about what they defined at their system, which as a nice element of the task. Different groups defined their systems differently and took different approaches to solving their vector addition diagrams, which lead to some fantastic conversations when groups who finished early compared results. I got really happy when I overhead a student slowing down his group down by telling them the process is more important than the answer, and even used the fact that I couldn’t remember the masses I used as evidence.

During prep today, I got a kick out of grading quizzes. I’ve been asking students this year to self-assess and do a short reflection on each quiz, and several students took that into specific problems on this quiz. These students wrote down some really interesting, specific metacognition right alongside their solutions without any extra prompting. It was really interesting to read. I might start having students do some journaling later this tri to explicitly encourage that kind of thinking.

Physical Science: Field Lines

To help make sense of magnetic field lines, I had students connect gravitational energy to a topographic map of a hill, then went back to the magnetic field lines we saw yesterday to talk about magnetic energy. I haven’t done any forces with this class yet, but they are fairly solid on energy, so magnetic energy seemed to help ground the material in a way I don’t think forces would have. I also like that the topographic map helped link back to some of the map interpretation students did first tri in Earth Science.

# Day 73: Force Vector Addition & Magnets

AP Physics: Force Vector Addition

Students worked some problems with balanced forces in two dimensions. We also had some discussion about whether you could have a mass hanging from a perfectly horizontal rope and used some hanging masses and string to experiment with some of the ideas. Not surprisingly, they really wanted it to work with a small enough mass in the center and a large enough force on either side, but once they started drawing free-body diagrams, it became very clear that the rope has to flex.

Physical Science: Magnets

Students played with some bar magnets and steel filings to start building some ideas about magnetic fields. Every year, my 9th graders struggle to see patterns in the filings, even when they are very clear to me. I usually have them start with the filings, then get out a compass to compare the patterns. Next year, I might have them plot the orientations of a compass arrow first, giving them some specific positions around the magnet to check, then get out the filings. That should give them an idea of what to look for in the filings.

# 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 101: Right Hand Rule & Solubility

Physics: Right Hand Rule

I introduced students to the right hand rule, then had them work through some problems applying it. Next year, I need to get some concrete, first-hand examples; I’d love to find a beefy enough horseshoe magnet to deflect a length of wire. Students did make some nice connections to projectile motion when looking at the path of a charged particle.

Chemistry: Solubility

We had some post-lab discussion on yesterday’s solubility lab. I tried to focus the conversation on evidence, since my students often get caught up in focusing on the answer alone. We also talked about some graph interpretation, such as what their sugar dissolved vs. temperature graphs should look like if there were no relationship and why many of their graphs look linear, while the “real” graph is a curve.

# Day 100: Magnetic Field from a Wire & Solubility of Sugar

Physics: Magnetic Field from a Wire

Students made some observations of the deflection of a compass around a current-carrying wire. Results were okay; I think I need to find some resistors that can handle bigger currents to make the effects more visible.

Chemistry: Solubility of Sugar

Students measured how much sugar they could dissolve in water at different temperatures to produce a solubility curve.

# Day 99: Magnets & Concentration

Physics: Magnets

Students used yesterday’s observations to start sketching magnetic field lines. I also had them try to magnetize different materials; a lot were surprised to find that copper wire didn’t respond to their magnets. I ended by dropping a strong magnet through a copper pipe to give them something to puzzle over during the long weekend.

Chemiatry: Concentration

Students worked some concentration problems. I tried to take the opportunity to focus on more familiar contexts for problems, basing problems on what you could get at a drug store or grocery store, and the concrete settings seemed to help a lot of students.

# Day 98: Magnets & Solutions

Physics: Magnets

Students used compasses, iron filings, and bar magnets to start exploring magnetic fields. Students are getting more skilled at finding ways to dig into a new phenomena and a lot of groups made observations that started to show how the magnetic force depends on distance.

Chemistry: Solutions

We broke out the textbooks to introduce some vocabulary related to solutions. Students were able to find some connections between concentration and percent composition, which was great given that many of my students started the trimester seeing what happens in school, and especially science classes, as a series of confusing, unrelated events.

# Day 39: Magnetic Fields & 2D Forces

Physical Science: Magnetic Fields

My students have gotten really good at looking at new content in terms of energy, so I put together an assignment to compare topographic maps as a measure of gravitational potential to magnetic field lines as a measure of magnetic potential. The assignment needs some revisions, but I like the basic premise and my students definitely understand magnetic field lines much better than my students have in the past.

Physics: 2D Forces

A lot of students were on a field trip yesterday, so we used whiteboard speed dating to go over yesterday’s problems. Based on what I saw and heard, students have these problems down better than they give themselves credit for. I’m thinking about how I can adjust my plans tomorrow to help students feel more confident with the material without resorting to me doing an example at the board.

# Day 38: Magnetic Fields & Vector Addition

Physical Science: Magnetic Fields

To introduce magnetic fields, I had students play around with a bar magnet, some filings, and a compass. Several groups were really fascinated by the compass, and there was a lot of discussion about why the north indicator on the compass go would to the south pole of the magnet. I also decided we need to revisit forces tomorrow. A group noticed that the magnet made some of the filings stand straight up and was trying to figure out why, which was great! The problem is the best why they could come up with is “magnets break gravity.” I’m pretty sure students just don’t have the idea of balanced forces well enough to come up with the idea that the magnet must exert a force to balance gravity.

“Magnets break gravity”