Waves

Day 118: Giant Pendulum & Conservation of Mass

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Physics: Big Pendulum

Before discussing the results of yesterday’s pendulum lab, we went to the main entrance of the school where we could hang a string from the second floor down to the first to make a 5 m long pendulum. Students used their mathematical models to predict what the period should be. Most groups used a linear fit for their data, and ended up predicting a period that was too big as a result. The really long pendulum provided a reason to refine their models by collecting more data and trying some linearization.

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Chemistry: Conservation of Mass

Students reacted calcium chloride, baking soda, and bromthymol blue in a Ziploc bag, making sure to take the mass of everything at various stages. This tri, I gave each group a beaker to place their bag in when using the balance, rather than having them set the bag directly on the balance pan, and the results were much better; students were able to use their results to articulate the law of conservation of mass very nicely.

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Day 117: Pendulums & Mystery Tubes

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Physics: Pendulums

Students started collecting data to make a mathematical model for the period of a pendulum. This is the first lab that was framed more generally as make a model, rather than as to find a relationship between two variables, so we started with some discussion about what variables could matter. Today was one of those days where I felt a bit extraneous; students are getting pretty good at designing experiments and deciding how much data is “enough”, so I wasn’t fielding many questions.

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Chemistry: Mystery Tubes

With the start of a new tri, I restarted the course today with a new group of students. This time, I decided to start with the mystery tubes. Students practiced making observations, then forming and testing hypotheses to figure out what is going on inside the tube. We wrapped up with a brief discussion comparing the tubes to learning chemistry and I introduced the idea of chemistry as a series of models that make good predictions, rather than a set of facts.

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Day 54: Refraction & Final Review

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Physical Science: Refraction

Students stuck pens, pennies, and other assorted objects into cups of water to develop some ideas about refraction. Students were very quick to connect their observations in the lab to their experiences from outside the classroom. The couple of students who’ve been bow or spear fishing were especially excited.IMG_1470

Students also made some observations of a laser pointer shining into a tank, aided by some creamer in the water and chalk dust in the air. It made a huge impression on these students when I used the chalk dust and laser pointer to show reflection yesterday, so they were thrilled to see it was still out today.

One particularly observant student noticed they could see three bright dots when the beam hit the side of the thank. We talked a bit about it, even though the students have only pretty rudimentary tools for talking about the behavior of light, and they decided that the center spot was the light reaching the outside edge of the glass while the outer spots was the light hitting the inside edge of the glass. Given the way this course skims the surface of each topic, I was pleased with their conclusion.

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Physics: Final Review

Students took their last quiz of the trimester, covering projectiles, then started working on their final review. The review is mostly a packet of their quizzes from this trimester.

Day 53: Reflection & Projectiles Practical

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Physical Science: Reflection

Students used reflectors (like this one) to explore reflection. I gave them some very general questions and directed them to collect evidence that would allow them to answer the questions. Students had some trouble getting started, but did a nice job overall.

Physics: Projectile Practical

Yesterday, each group was given a distance from a projectile launcher and had to calculate how high above the ground the projectile should be. Today, students placed embroidery hoops at their predicted height and we fired the launcher.

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Day 52: Color & Projectile Practical

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Physical Science: Color

Students used colored filters, felt, and light sources to find patterns in what determines what color they see. By the end of the hour, students were able to use what they saw in the lab to accurately explain their observations in the filters puzzle video.

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Physics: Projectiles Practical

Students began a lab practical for projectile motion. First, we fired a projectile launcher horizontally and measured the range and starting height to determine the launch speed. Then, each group got a different distance from the launcher and calculated how high off the ground the projectile will be at that point if the launcher is fired at an angle of 45 degrees. Tomorrow, each group will place an embroidery hoop at their given distance and calculated height.

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Day 51: Color Intro & Collaborative Problem Solving

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Physical Science: Color Intro

For the first half of the period today, my students presented their research projects on different energy sources. Once that was finished, we started on color. I started by having students watch a short video that I blatantly copied from Frank Noschese that shows red ink and red light through both red and blue filters. I like the video because I can show all my students at once and I like having my own version so students can look at the clock and paper I used in the video to verify I wasn’t using some kind of trickery. I asked students to record their observations from the video, then try to come up with a hypothesis to explain their observations. This lead nicely into a lab where students look at things through filter paddles. Once students finish the lab, we’ll revisit the video to see how their explanation has changed.

Physics: Collaborative Problem Solving

I took a problem from Casey Rutherford’s projectile motion packet about a block given a push up a ramp with friction, then allowed to fly off the end of the ramp to become a projectile. One of the things I love about this problem is it requires to students to use just about everything from the trimester. 2nd hour, students did whiteboard speed dating, but I put a couple of goal-less problems first so students didn’t have much time to work on it, but were intrigued enough by the problem that they asked to continue next week. 4th hour, I decided to start with that problem. I had students work in groups using the roles from the University of Minnesota’s Cooperative Group Problem Solving protocol. It took most of the hour, but students were consistently successful and even my top students were challenged. It was great to see the obvious pride when students finally got the correct answer.

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Day 50: EM Spectrum & Projectiles

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Physical Science: EM Spectrum

Students made a scale model of infrared through ultraviolet light where the length of the paper represented the wavelength of each type of light. I also had students do the calculations for how long a strip of paper would be needed to represent some other EM waves, including radio waves and gamma rays, just to give them a sense of the range the EM spectrum covers.

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One group decided to turn their model into a Stroop test

Physics: Projectile Problems

Students whiteboarded yesterday’s projectile problems. I’m really pleased by the way my students are not only solving the problems successfully, but gaining confidence on some challenging material.

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Day 49: Light Intro & Projectile Problems

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Physical Science: Light Intro

After a short quiz on sound and some discussion over final exams, I did some notes to define the term “electromagnetic spectrum”, reviewed scientific notation, and gave students the speed of light. The class was really fascinated by the speed of light and were eager to spend some time throwing out questions about the implications of light having a speed like “Does that mean some of the stars we see are already dead?” I gave the class some room to discuss what they thought about these questions, which prompted even more questions, which was great! The discussion went long enough that the students didn’t get to the lab, but I was okay with it since students were doing a lot of great thinking.

Physics: Projectile Problems

Students worked on calculations for projectiles launched at angles.I’m still having students use velocity vs. time graphs, rather than the standard equations, and students did really well with some challenging problems today. Tomorrow, we’ll whiteboard the problems.

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Day 48: Experimental Error & TIPERs Projectiles

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Physical Science: Experimental Error

Students calculated the speed of sound based on the data they collected yesterday, then compared that to the expected result. Students found the speed using five different tuning forks, so we had some discussion about what it meant for those two different speeds to be close enough to be considered the same, which lead to some good conversation about experimental errors and why the values varied.

Physics: TIPERs Projectile Questions

I picked some questions out of TIPERs to help get my students thinking conceptually about projectiles. I was surprised at how many students struggled with a certain question where a ball is thrown upwards at two different speeds, and a student in the problem predicts that the faster projectile will reach the highest point first. Once I prompted students to sketch velocity vs. time graphs, the question ended up being pretty easy. It was a good reminder for my students to look at what tools they have, even when the problem isn’t about a calculation.

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The faster object reaches its highest point in more time!

Today’s quiz on projectiles launched horizontally also reminded me why I love standards-based grading. Several students have been really working on solving problems with constant velocity and constant acceleration, and finally showed mastery when they applied those skills to projectiles today. I loved being able to give them credit for all the skills they showed, not just the big idea on today’s quiz.

Day 47: Speed of Sound & Projectiles Practical

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Physical Science: Speed of Sound

Students worked on the classic speed of sound lab using a closed resonance tube. Since this is one of the first labs my 9th graders do that has an accepted value, it provides a great opportunity for discussion on experimental error, which will happen once students finish the lab tomorrow.

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Physics: Projectiles Practical

Students did a lab practical for projectile motion where they had to predict where on the ground a marble would land after being sent down a short ramp. In the past, I’ve used a cup, but most students hit the side rather than landing in it, so this year I used the school’s retired referral forms as carbon paper. I also pulled a jerk physics teacher move. After students got a successful prediction, I gave them a marble with a different mass and had them predict where the new marble would land without allowing them to make any new measurements. Most groups had to wrestle with it for a while and even try some calculations before realizing it should land in the same spot. I decided I need to keep this extra challenge in the practical when one student victoriously declared “Misconception changed!” after hitting their prediction with the new mass.

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