# Day 17

Physical Science: Today we talked about SI Prefixes and also setting up ratios for unit conversions. Not real exciting, but tomorrow we will be working on practice. Should be interesting to see how they do.

Chemistry: Instead of collecting lab books today for our Mass and Volume lab, I let the kids keep them for a few more days. This gives them some resources for the big Density assignment that I gave out. We will have lots of white boarding going on tomorrow, lots of good discussions.

Physics of Light: So today we got ready for the white boarding sessions. Here is a look at the raw data and graphs that the kids ended up with.

So 3 groups got some really nice looking, linear graphs. The white boards that got presented today looked like this:

That last board is a classic. Notice the drawings at the top? Those are ducks, with 5 light particles in them. Then he drew a bigger duck, same particles, but more spread out. It was a good visual for what was happening. So I posed this question:

“How much does the illumination change if we double the distance from the source?”

This lead to the “triangles” at the top of the page, and using 3-4-5 triangle to show the difference. Ultimately it came out to 1/2 the illumination, but the 3D nature of light was ignored.

That’s when I dropped this on them:

That is a physical model of the inverse square law. It shows how when you double the distance from the point on the light source, the area the light spreads out over is 4 times as great. In terms of illumination versus distance: when the distance from source increases by a factor of 2, the illumination goes down by a fact of 4.

Then the bell rang, so we have to finish it up tomorrow.

Advertisements