180: Day 26: How does GPS work?

students creating scale models of GPS satellite orbits

Two summers ago I was able to attend the Einstein Plus workshop at the Perimeter Institute for Theoretical Physics. They provided some great mini-units on ‘Modern Physics’ topics, and I’ve tried to figure out a way to integrate these into my class. This year I realized I could use them as “filler” during our seniors’ Kairos retreats (students are gone for three days, which means I don’t see some of them all week!). I’m pulling out a couple of days worth of work from each unit, and the students who are on the retreat don’t have to make it up (they always have too much to make up anyway). This way, each student will get four mini-units, and miss one.

Today we started Everyday Einstein: GPS & Relativity. Students watch a short video about GPS (8 minutes), then explore uses of GPS, create scale drawings of the GPS satellites above the earth, make some calculations about the time between signal broadcast and its arrival on earth, and finally use an online mapping site to triangulate the position of an object given three cities and distances (would work great for earthquake epicenter location as well). We didn’t get as far as I had hoped, but we can finish the geolocating tomorrow, then start on relativity.

students creating scale models of GPS satellite orbits
Students drawing scale models of the height of GPS satellites vs radius of earth. One group also added the International Space Station, and, with prompting, added the height of the atmosphere.

180: Day 25: Faculty/staff retreat

Lee's sketch from Mont La Salle

Today we had a faculty/staff retreat at Mont La Salle at the Christian Brothers Retreat and Conference Center in Napa, CA. During the welcome/introduction, our principal suggested that we turn off our phones for the four hours. I thought that sounded like a good idea, and turned mine off. Reflecting on our sense of “need” to be connected, I thought about emergencies that might happen that might need my attention, but I couldn’t come up with any that couldn’t wait the four hours. After all, a couple of decades ago I did not expect people to be able to contact me 24/7, so why can’t I do that now?

During a break-out session, I had an hour to do some journaling/reflection, and found a nice shady spot with a beautiful view of the hills of the Napa Valley. My first thought was to take a photo, but then I realized that would require me to turn on my phone. Now, I’m no sketching artist, but I took this as an opportunity to try out some sketching. Attached is the sketch I made. It’s not really to scale, and isn’t in ‘millions of colors,’ but I can look at it and remember where I was–and isn’t that one of the main points of a photograph?

Lee's sketch from Mont La Salle

180: Day 24: Fundraising for the whole school

SHCP 2015 Walkathon image

Most schools these days need to do fundraising, whether they be public or private. The last two weeks at Sacred Heart Cathedral has been “Walkathon weeks.” Students collect donations from relatives, neighbors, and friends. It’s our one big student fundraiser of the year. The final day is the Walkathon itself. Students meet at the Polo Fields in Golden Gate Park. After taking roll and some spirit-building games, we’re off on the walk. Four miles later, we’re back in the bleachers for a bit more spirit, then everyone walks to the nearby meadow for lunch. After lunch, students and teachers are free to go.

I enjoyed the walkathon, and think it’s a great opportunity for community building (as well as to make some money). Having a full day (well, half-day in reality) where our community gets together without academics or athletics gives us a chance to chat and just enjoy life together. The parent volunteers are wonderful, and lunch is a great finisher for the day (they even had plenty of vegi-burgers!). Since they have the afternoon off, I heard about some of the students were heading down to the beach (September in San Francisco tend to have the most sun, and we lucked out this weekend).

This might be harder for a public school to pull 0ff (in California, there is a minimum number of hours required to make a day count as a “full day” for finances), but I think it could be done. SHC has worked out many details in 26 years; if you’re interested in more details, here’s the Walkathon home page, or leave a question in the comments section below.

It will be a great day when we don’t have to have fundraisers in schools, but in the mean time, this model is a great one.

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180: Day 21: Final suggestions/tips for buggy collision challenge.

photo of students determining the speed of their buggy.

Buggy collision prediction sheet lined up with a meter stick.Last blocks with buggies: Here’s another close up of the target sheets I use with my students. The complete the top, then find where on the row of four metersticks they need to place their prediction. I give not help at this point, and often ask “Are you sure it’s in the right place?” (even when it is). I try to involve all six to eight students in the trial (two combined groups of 3-4 each). When they are done, there is homework for them to work on in class.

A few tips:

  • Even with only four or five tests required (eight to ten groups), there is still down time for many students, so make sure you have something else for them to do. I always have that day’s worksheet/night’s homework ready for them. Next year, I plan to have something more in line with a conclusion on the lab.
  • My target has a very low “A” range, so, as I said yesterday, any group that lands on the paper gets an A.
  • Have them measure and calculate the speed of their buggy on the day of the collision test. This should take about five minutes, then ten minutes to make their prediction. If they use speeds from previous days, the batteries may have weakened and slowed the buggy down.
  • Use the “testing” time with your small groups to confirm they understand the placement of their paper. I often ask “Does this position make sense?”–to which they should answer “Yes, because the fast car will move a greater distance” or something along this line.
photo of students determining the speed of their buggy.
Students making measurements to determine the speed of their car right before the collision challenge.

180: Day 20: “One train leave a station at 2:30, and another train leaves…

Buggy collision prediction sheet lined up with a meter stick.

Here’s a classic physics problem:
1918trainwreck

One train leaves a station at 2:30 at a speed of 40 m/s,
and a second train leaves another station at 50 m/s.
The stations are 40 km apart, and the trains are heading
toward each other. At what time and position will the
trains collide?

These days, many teachers use this as a chance for an actual experiment. I challenge my students to determine the speed of their cars, then I match them up with a random group (well I know each group has a car with a different speed). They then need to calculate the position the cars will collide if they start four meters apart. I have a grade sheet that shows them their grade. My standard sheet has A-D on it, with A at the center where the cars are due to collide.

With each buggies traveling 1.2-3.8 meters, I probably should give them a bit more slack in the “A” range, so I’m thinking that for next year I may use three sheets of paper with most of the center one being the “A”, and the outside ones being B-D.

I like this lab because it’s easy to get correct predictions, and students have to go back and check their math if they don’t get an “A”.

Here’s a video showing an accurate prediction. The class, and I, get quite excited as the collision moment approaches!

180: Day 18-19: Introducing Motion Maps

photo showing cars and position marks on board

OK, I’m cheating a bit, but I do teach the same classes on Thursday/Friday this week.

I tried  a new technique this year for introducing motion maps. I stood at the board and asked a student to call off every second. I started a car moving at the base of the boards (my new classroom has floor-to-ceiling whiteboards), then draw a mark at the location of the car each time the student called out a second. Asked students what the dots told them, and they replied that since they are the same distance apart, the car is going at a constant velocity (yay!!!).

photo of tumble buggie cartsNext, I put the same car at the right side of the board and, with my student calling time, marked the position of the car going in the opposite direction. Asked class what the dots tell us–and they said it’s going at the same speed.

Then I asked ‘what’s missing’ from the diagram, and, with some false starts, they decided that direction was missing. ‘How could we identify direction?’ ‘Arrows!’ they answer. So, I add arrows to the drawings.

Next I bring produce a faster car, and mark it off.

'What's the difference?'
'It's moving faster!'
'How do you know?'
'The arrows are further apart!'

Wow, almost there.

Finally, I take place a 2’x3′ whiteboard perpendicular to the wall (classroom has small slots between vertical panels that are just perfect to hold these whiteboards) and start a car towards it. These “Tumble Buggies” are designed so when they reach a wall they flip over and start in the reverse direction. While I’m marking the on the board, the car takes 2-3 seconds to flip, and I have a few marks on top of each other (I purposely put them not quite on top).

'How long did the car not move forward or backwards?
'Three seconds.'
'How would you show a dot for an object that is not moving?'
'Huh?'
'How would you show a car with a very slow speed?'
'A very short arrow.'
'So, how would you represent an object that is not moving?
'A dot with no arrow!'

I then ask them what the graph of these would look like, and we draw it on the board, starting with the first car and soliciting questions after each graph.

Finally,  I ask students to describe the motion of each car in words.

'A is moving forward slowly.'
'B is moving backwards at the same speed.'
'C is moving faster.'
'I what direction?'
'Forward!'
'D moved forward slowly, stopped for a few seconds, then returned to where it started.'

After this, it’s off to the “Motion Maps and Position vs. Time Graphs” worksheet (I also have my revised version of the traditional Modeling Instruction motion map reading online for them as a back up).

“Notes for next time”

I think I’ll roll one of my tables up against the wall, to make it easier for all students to see. Someone Tweeted about a “Fridge Rover” can that can roll on metal vertical surfaces, but I find having the car able to turn around more important that having it roll on the wall 🙂

photo showing cars and position marks on board
Here’s the finished product, with the buggies in there just for show.

180: Day 17: Short period, a quiz, and Ahmed

screen shot of a Desmos plot

I’m getting so used to 80 minute blocks that I’m not sure how to handle a 40 minute period when it gets thrown at me. Today was a 40 minute period day (five classes in one day, how did I ever handle this?), and I threw a quiz at my students in which they had to use Desmos to plot some data and answer some questions. I love Desmos, but from the results it seems like many of my students still aren’t getting it (I suspected many are letting their partners do the work, thus I gave them this quiz).

After the quiz, some students were discussing Ahmed Mohamed and his clock. We talked about it a bit as a class; I encouraged them to not immediately throw in the ‘race card’ without knowing more about the school (it’s very diverse, as is the administration and faculty). I did not deny that racism may have been involved, but I suggested they not call someone names unless they know more of the details.

Here’s a petition I wrote asking the principal and police chief to apologize to Ahmed. It has about 6,000 signatures in the first 24 hours, and it was mentioned in Cosmo!

180: Day 16: Whiteboards are improving

photo of another example whiteboard

The first few whiteboards always take longer than I want. Often, student’s aren’t prepared (haven’t already analyzed the info with their group), don’t understand how to back up their conclusions with evidence, and don’t get how to translate words like “rate” or “speed” into simple English sentences that don’t use those words.

But today they are doing better (paradigm lab #2), and I’m spending the time with most group to ensure that their boards at least contain much of the necessary info.

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180: Day 15: Empathy for teachers slow to picking up technology

photo of corner of Empathy Place and Perservierance Ct

No photo or classroom activity today; instead a reflection from a training on our school’s LMS (Schoology):

One of our tech folks was leading a brief afternoon gathering for questions from teachers new to Schoology. Mr. Vito Ferrante, our Director of Educational Technology and an Instructor of Mathematics–whose job it is to help teachers learn to use our computers–made a comment I probably can’t do justice to, but I’ll try. He said something along the lines of ‘veteran teachers who are not jumping on the bandwagon of tech in the classroom may have been great teachers for years–but now they are being asked to become beginners all over again.’

As a 55-year-old who has been teaching for 20 years, I have tended to have little patience for veteran teachers who resist using technology in their classroom and in their grade book. ‘If I can learn it, why can’t they,’ has often been my attitude.

But Vito has given me cause to be more empathetic with these teachers. Not that I don’t want them to learn tech and implement tech in their classrooms, but just that I probably should give them more emotional space. In the past 20 years, my job assignment has been up to 40% FTE in tech support, and teachers usually have given me appreciation for my patience and gentleness in tech training, but it’s still important to remember how resistant we can be to making changes from a place of strength.

180: Day 14: Evaluating data from all classes

results sorted by color

I’m a big one on looking at large quantities of data. In each of my physics classes, I have seven to nine groups. In the Buggy Lab, that provides enough data that whiteboard sessions go fairly well, with:

  • at 3-4 groups going in each direction
  • two groups starting at extreme positive or negative locations
  • three to four starting at medium locations
  • two groups starting at zero
  • three to five slow cars and three to five fast cars.

But that’s not enough for me 🙂

I have my students submit their calculated results to a Google spreadsheet, so we end up with around 30 different sets of results. When we have our whiteboard meetings, I’ll have the spreadsheet available if students want to look at more data (and, of course, I hint that this would be a good idea).

Here are some results from this year (homework is to complete it, so not everyone has posted yet). I use Format…Conditional formatting… rules to add color based on the values.

results sorted by y intercept
Buggy lab data export by y intercept
results sorted by slope
Buggy lab data export by slope
results sorted by color
Buggy lab data export by color