Physics & Physical Science Demos, Labs, & Projects for High School Teachers

Archive for the ‘Activities’ Category

I’ve been a member of American Association of Physics Teachers for about 6 years now.  If you teach physics, please join!  The journals and posters alone are worth the tax deductable annual dues.  I attended my first AAPT meeting a couple of weeks back.  I learned one or two great new things, met some super people, but I was also a bit disappointed.

Let’s get the negative stuff out of the way.

  • I’m used to NSTA, so maybe my reference is unfair.  AAPT was small, really small for a national conference.  I felt like everybody knew each other because it was the same people every year.  You could get through the entire exhibit areas in about an hour.
  • It also felt like the conference was aimed at college educators.  I know the organizers claim it’s not, but I’m giving my opinion here based on attending one day of a much longer conference.
  • I had hoped that the talk on video in the classroom would give lots of useful tips; how to integrate video, success at flipping the classroom, etc.  Most of the discussion was why video lectures won’t replace colleges.

Now the positives:

  • The first timer special and lunch was a great idea.  Lunch and the company was terrific, I’m glad I went.  The first timer $75 one-day special is a great way to try it out.
  • I got to meet some great people, some new, some who I had previously met online (Kathy, Frank).  Everybody was warm and there to interact and learn from each other.
  • I met local AAPT members who are trying to suck me in to local activities.  I am interest, but they always do them on a Friday night and Saturday.  I may submit, I do need local physics buddies but I love my weekends.
  • Andy Rundquist demonstrated a great use of Jing.  He has his students take a picture of their homework, then narrate the work on video.  The video is their homework submission.  Jing limits them to 5 minutes and when they talk, you can immediately tell if they know what they are talking about.  Andy has them do this for every homework, I’m going to use it sparingly.  Super idea.
  • There is free software out there called Tracker that does video analysis.  One cool use was to take a moving object, like a person jumping into the water, identify several points (hands, feet, head) through each frame, and let the software determine the center of gravity and plot  the motion.  Did I mention free?
  • I really like the sessions where there is a new presenter every 10 minutes.  Lots of great stuff, and if it isn’t, it’s only 10 minutes until the next one.

AAPT was worth my time, I wish I had done the entire week.  It was close enough to home that I was able to take public transportation.  Here’s the problem: if you can get your school to pay for you to travel to one national conference, which do you choose – AAPT or NSTA?

For me, it would be an easy choice.  NSTA has so much more to offer, so many more strands, talks, exhibitors, and people to interact with.  I would love to do both, I don’t see how.  I will get involved locally, AAPT is too good of an organization to ignore, they are worthy of our support.

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This is not a new topic for me, it’s been a burr in my saddle for some time now.  All of the introductory physics textbooks address significant figures in much the same way.  The problem is – nobody in the “real world” uses sig figs.  At the same time, introductory physics isn’t the time to introduce complex error analysis models.

I’m having this discussion with Andy Rundquist of Hamline University.  I asked Andy how they handled this at the college level.  He told me they don’t teach significant figures and pointed me to a very lengthy article discussing why significant figures are all wrong.  The article suggests the use of Monte Carlo analysis its place.  That may make sense on a lab, but not on classwork and homework problems.  The uncertainty article did have a suggestion; use six significant figures for calculations and round the final answer to three sig figs.  The article does a good job explaining the reasoning, and I’m fine with it.  The three extra “guard digits” preserve the accuracy, and the rounding makes the answer more reasonable.

The next step is trying to explain uncertainty and significance of our data.  I came up with an activity I think will work:

  • I will project an archery target on the board.
  • Students will move back about 20 feet and shoot a round of Nerf darts at the target.  They will be far enough back that most of them will shoot a 6, or 7 and not a 9 or 10, at least at first.  Each student will take a turn.
  • We will plot the overall results.  We should get something resembling a normal distribution curve, but I won’t tell them that.
  • I will ask the kids to average the data and come up with a value of x.x +/- y.y and start a discussion on whether or not that represents the data.
  • We will then put a ring or other object on an electronic scale and write the mass with the error in the same way.
  • After some discussion, I will bring up slides of normal, rectangular, triangular, and maybe exponential distribution curves.  I want them to discuss the fit of the models to the data.
  • My goal is that they understand that error is probability.
  • About a week later we will drop rulers and calculate individual reaction times.  This would be a good time to bring back the distribution graphs and perhaps even input our data into a statistical analysis program to find the best fit.

I think this will work and go over well.  I’d love some feedback.  It’s a first pass, what did I miss?

First, let me be completely up front.  I borrowed this activity from my pal Deborah Carder.  You can find her link in my blogroll, she does great hands-on activities and labs.  I met her at NSTA Philly last year, she is the Energizer Bunny of science teachers, I don’t know how she does it.

Anyway, as I had mentioned in earlier posts on momentum, I wanted to do the egg drop competition, but I’m in a one-story building.  This year we are doing the “Egg Crash” competition.  The basic concept is that teams get 10 sheets of computer paper, 1 meter of masking tape, a pair of scissors, and 20 minutes to construct a free-standing object to safely catch the egg.  They drop their own egg from a height starting at 0.5 meters above the top of their structure.  The egg is inspected before and after each drop, the higher they go, the more points they win.  The surviving eggs are dropped from 0.5 meters higher each round until they all finally break.

I usually allot 25 points for a lab, I will probably go 50 for this one.  Deb said she does 100 points, but that’s a test grade and I don’t think a one-day lab should be worth that much.  I’m still working out the scoring, but I think I will assign a grade to each height.  If they fail at 0.5 m above their structure, they get 30/50, but they also get a single start-over with a new egg.  Each 0.5 m interval earns 5 more points.  That means surviving 2.0 m earns 50/50.  I’m willing to give 5 or 10 extra credit points if they can survive a drop from 2.5 or 3.o meters over the top.  I was going to do direct competition for the points, but what if everyone fails at 1.0 meters?  With my grading system, they all get 70% since nobody really earned the A or B.

I handed out the Egg Crash Description and Rules on the day we started learning about Momentum.  I told them it will be about a week before we do the competition; I wanted them thinking about the problem and their design as we learn about momentum and impulse.  This week I will show a great video called “Car Crash Tech.”  The video discusses the state of the art auto safety systems and the effects of air bags and other innovations.

I’m hoping for some creative solutions from the kids.  Maybe I’ll have a picture or two to post here in a couple of weeks.

Okay, I’ve been a bad boy.  It was more than a year ago I said I would update the post with the instructions.  You guys didn’t call me on it, so I forgot.  The original post is here along with a pdf of the plans I had printed for myself:

Original Tissue Paper Hot Air Balloon Post

The original plans make a balloon that is 60 inches high.  That is perfect for the classroom, it takes three pieces of tissue paper per panel and you need six panels.  You will find I went big on this one and made a 90 inch version for myself.  It is rather unwieldy and difficult to handle, but bigger balloon means bigger lift.  At this point, I can put one of these 60″ balloon together in about an hour, where it takes the kids at least 2 hours.

One of the challenges we ran into was finding the aluminum wire we used to keep the mouth open.  You want this for two important reasons; first, to add ballast; but more importantly, without it, the kids can’t catch the balloons on their heads.  I found the wire at Dick Blick, an art supply store.  They list it under sculpture wire, we use the 14 gauge wire.  It costs $16 for a 350 foot spool.  Each balloon uses about 3 feet.  That’s a lot of hot air balloons.

When it is too windy outside, we tend to launch these in the gym.  I have two heat sources.  The indoor one is a heat gun I purchased from Harbor Freight on sale for $10.  It works great, I make sure I handle it so nobody gets burned.  The outside source is a plumbers propane torch.  Nobody handles that but me, I don’t need to write up any (more) accident reports.  If you are using the torch, make sure the kids keep the balloon opened up, if you aren’t careful you can catch the balloon on fire.  Oops, only did that once, very cool though.  If you do that, light it from the bottom, it goes up into the air and disintegrates … poof.  Bad science teacher.

Some day I may make one of those cool chimney launchers, but then I’ll have to store it in my room.  It’s already looking like Sanford and Sons in my classroom, I don’t know how much more junk I can store.

Tomorrow the students learn just how big our solar system is and just how small we are.  We will use the attached worksheet to calculate the percent distance from Pluto for the planets in our solar system and our nearest neighbor, Proxima Centauri.

Solar System – Size and Scale

To make this lesson really stick, we first calculate the percentages, then we lay out a long 100 meter tape outside.  Students volunteer to be objects and they get a card with the picture of that object on it.  Now we place them on the scale based on their percentage distance.  The Sun is at the zero point, Mercury being only 1% of the distance to Pluto is at 1 meter.  Earth is at 3 meters, Mars is at 4 meters.  Jupiter jumps to 13 meters from the Sun.  Pluto is at the 100 meter mark.

In addition to the vast distances, I then discuss how big these objects would be at this scale.  The Sun, as huge as it is, is only 2.4 cm or 1 inch in diameter.  The Earth would be 0.2 mm, about the size of the period at the end of a sentence.

We discuss how long it takes to get from the Earth to Mars (a 6 month trip by rocket).  The people who are Earth and Mars are fighting for space on the tape, it’s crowded near the Sun.  After they start to get a sense of scale, I hit them with this.  At this scale, the next closes star,  Proxima Centauri, is 676 km (420 miles) away, or roughly the distance from Philadelphia to Portland, Maine.

I mentioned this in my previous blog post.  No strings attached, NASA has a number of robotic telescopes out there for real work that is available to the public.  How cool is this?

Essentially there is a network of these things out there for researchers and educators and the public to use.  You just need to know they exist, and now you do.  For non-researchers, these robotic telescopes have their interface simplified to make taking pictures relatively painless and error free.  These robots sit in a field, all alone, with nobody to talk to, just taking orders for pictures.

There is only a small catalog of 36 objects, not all of which will be visible that evening.  Pick one, then the interface asks you for a field of view.  For those of you who have never used a telescope, it is essentially a zoom level.  For the common folk, you only have one choice, but you do have to select it.  Next is the time of exposure.  It gives you several options, but it will tell you if it is too long or too short.  Last is the filter.  Some objects have no filter, others have red, green, and blue.  Click on continue, give them an email address, and you will have your pictures delivered some time the next day.  I’ve tried it twice now, each time the pictures have arrived after lunch the following day.

Harvard Smithsonian Micro-observatory Link

If you aren’t aware of how astronomical photos are made, here is a quick lesson.  Pictures are taken through different color filters.  Through a telescope or the naked eye, everything is just shades of gray.  But if you take it through RGB filters, you end up with three different images.  Now you color each of those images separately and use special software to merge them into a single image.  Ta-da!  A full color image you created.

Okay, there is more.  Astronomy photos are typically in a format called fits.  These images carry tons of information about where, when, settings, etc.  You really need a special package to merge these photos, but you are in luck.  On the same page is free software and a tutorial to do all this.

Imagine how excited your students will be.  You teach them about how light is gathered by a telescope.  You talk about how the filters are needed to show the color.  The color is real, we just can’t see it, there aren’t enough photons for our eyes.  Next up, the students go to the site and select an object to photograph.  Their request goes into the queue.  Multiple requests of the same object will each have individual pictures.  Now you can have them walk through the tutorial and use their own image to combine and create their own astronomical photo.  Once done, I would send the lot off to Walmart or CVS or some other inexpensive photo developer and they get to put their own astronomical photo on the fridge.  Seriously, I get goosebumps thinking about this lesson.

Like I said, this little secret was worth the cost of NSTA.  And I almost stayed home on Saturday.

Cards on the table… I outright stole this project.  My daughter was competing in the Physics Olympiad this weekend and one of the activities was to build a tower of marshmallows and toothpicks that can support a ping pong ball.  I know it’s not new, but I had never watched it happen before, I’m sold.

This was a great exercise in teamwork and engineering.  I was rather impressed at how the whole project came together in just 25 minutes.  I wasn’t sure when I would do this in my classes, we don’t ever really study mechanical engineering principles.  The same with the basswood bridges they built.  The concepts are great, I love the hands-on, I just wasn’t sure where this would fit in my curriculum.  I decided that I am going to use the Tower of Marsh when we do a short chapter on Center of Gravity.  We can do a small side study of bridge design and then do a team activity building the towers.  I was going to give the kids 40 minutes, the 25 minutes they had seemed to fly by and I have a 55 minute class to fill.  Maybe as an added prize, the winning team would get to have hot chocolate with mini-marshmallows.

The attached instruction sheet has been modified for classroom use and includes how it will be scored.  This is in Word 2007 format, you may need a the free converter if you don’t have it yet.

Tower of Marsh


What’s New in 2013/2014?

Every year brings a change, this one is no exception.

I will be picking up the sophomore honors Algebra II class to keep them separate from the juniors. This should help accelerate them and put them on a stronger track towards Calculus. Looks like there will be only one section each of Physics and Calculus, but still two of Robotics & Engineering.

Hot topics this year are going to be the Common-Core Standards, Standards-Based Grading (SBG), improving AP Calculus scores, and somehow adding Python, maybe as a club.

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