Archive for April 2010
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.
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.
The kids use the multimeter to measure the capacitance of some rudimentary parallel plate capacitors made from Al foil (Note: the Harbor Freight multimeters do not measure a small enough capacitance for this lab…it’s in the nF range). I adapted this lab from somewhere but I can’t remember where are this point. I have attached both the lab and the graphical analysis I make available to them. I use this with my honors level class and they pretty much teach capacitors to themselves. I try to do a lot with proportionality with them throughout the year so they can start to develop their own mathematical models (especially with straight forward things like this). Although it’s a small step, having them develop their “own” models (or at least work through to find the equation) develops fundamental science skills necessary for research and enforces the fundamental content standards of NSTA.
The capacitance lab paper is attached here, but due to WordPress limitations, the spreadsheet links to Marcie’s web page at school.
I want to do some experiments with wax paper rolling them into canisters and maybe plywood sheets of known thickness. If I do, I’ll either add on to this post or create a new post with my results.