# First Day Demo

Posted on: June 2, 2008

I do this demonstration on the first day of school to get the students attention. After talking about the syllabus, what is physics, making them think, etc, I ask them which falls faster, a heavy object or a light object? I get the discussion going and everybody into it, then I jump up on my demonstration table, take off my shoe and ask which will hit the ground first, the pen in my hand or my shoe, which is now in my other hand. I drop them several times so that everybody sees they hit the ground at the same time.

I can’t tell you how many kids have told me they went home and did the same experiment. Sure it would work standing on the ground, but the act of climbing up on the table shakes them up and shows them this is going to be a different kind of class.

### 8 Responses to "First Day Demo"

I consider myself a lover of chemistry. When I decided to go into teaching I never thought about having to teach physics, I call it the p-word. Needless to say Iam new to teaching and this year I will have chemistry, physics, and physical science. So I have been searching the internet for small ways to make a subject I dread exciting for my students. Thanks for this one! It is something quick (that I understand which is a BIG deal) that I know will get a giggle.

Great idea! It’s so important to get the excited about science as quickly as possible when school starts. I love this idea! Thank you for sharing.

Here’s my first day exercise to get them thinking about experimental design, and hypothesizing about a physical situation:

I ask them whether a row of dominoes will fall faster if the dominoes are spread pretty far apart or closely spaced. Few seem to have a good instinct for the correct answer. I might get them thinking by noting that far apart means the falling domino gets up to a high speed, but it has to fall farther before hitting the next one. Opposite argument for the closely spaced. I give them a worksheet with boxes for their prediction, a description of how they will test it, and a space for results. They can then write up any applications they see of this new knowledge — other physical situations where the same principle applies.
Later in the year, we can refer to the experiment when we discuss sound in a medium, wavespeed, signal propagation in a solid, kinetic energy transfer among particles, etc!
I only had to buy about 6 boxes of dominoes, one for each lab group. They soon figure out that they can do a more convincing test if they combine with other groups — collaboration!
Steve

Dominoes, i like it!
My first thought was to design an experiment to find the optimum distance for the fastest speed. The distance would range from too far to too close to fall. times for each distance could be graphed as well as comparisons between groups to examine experimental error.

great idea — i’m going to try it in my Waves & Optics class (seniors) in a week — how many kids in each lab group? — any pitfalls you can warn me about? — any suggestions to make this go smoother?
thanks,
mita

It’s great for getting them to form a mental model of atoms and molecules passing energy in the form of a wave. Pitfalls? Some groups will use a timer and attempt to time a run, but for 40-50 dominoes, the time is too short to be accurate, but they think they can trust the timing. So be sure to have them use 3 timers per trial so they see how much uncertainty there is. Also, some will think that using say 25 tiles closely spaced and 25 tiles widely spaced will allow them to compare speeds — it won’t because the distances won’t be the same. This can lead them to thinking more about the definition of speed or velocity. The ultimate way to settle it is to have groups combine and build side-by-side lines and then start them together. It’s quite convincing. Be sure to have some kids grab video of it on their phones!

Hmmmm. I think I will be visiting this site often this year. I am a biology and anatomy teacher, but I’m teaching a conceptual physics this year and in need of some ideas. Gee, I feel like a first year teacher again. Thank you for the ideas posted here!!

Great practical idea to enthuse students at the beginning of the school year!

I have written a popular article about the effects of gravity in an imaginary situation where Homer Simpson’s mass always stays the same but his weight changes depending what planet he visits!

Your students can check it out at newtonsapple.org.uk

### 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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