Thursday, December 15, 2011

Teaching Geography to 2nd Graders


My son is in second grade, and his teacher was absent for a couple of days this week so I volunteered to teach the geography lesson. I spent about 45 minutes teaching the kids about geographic projections. It was so much fun! The kids were all enthusiastic, attentive, observant, and lots of fun.

We started with a discussion about the shape of the Earth, using a globe as an example, and talked about why it's usually more convenient to have a flat map on paper or on a screen when you need to do something map related. Then we talked about how the transition is made from three dimensions to two, and I passed out a satsuma to every student. I asked them to pretend their orange was the Earth and asked them to transform the orange peel into a flat, rectangular surface. Before they began, I explained that there is no wrong or right solution, and that the task is in fact impossible--but it would be really interesting and fun to try to solve it. They worked cooperatively to complete their 'projections.' After all the kids were finished, they ate the oranges, then took turns table by table looking at the solutions generated by their classmates. I asked them to make observations:  what did the solutions have in common? how were they different? what conclusions could they draw? Then we gathered on the floor and they shared their observations.

This is the part that really blew me away--of course, they all quickly ascertained that it was a very tricky problem, but they also understood that for small areas, it was possible to minimize the distortion of the peel, and that certain patterns seemed easier to work with than others. Many of the kids kept their peels in one piece, some intentionally split them into numerous pieces and re-assembled it, and some did a bit of both. During the discussion, every student made an observation or asked a question, and many did both.

After the discussion I drew a picture illustrating the mechanics of translating the a sphere to a flat surface, then showed them a poster I prepared showing nine different global projections, ranging from Mercator to Sinusoidal to Goode-Homolosine. We didn't spend a ton of time on any particular projection, but we did discuss the various applications for some of them (i.e., Mercator is great for navigation but not so good for wall maps) and they all saw that the projections are just as varied as their orange-peel solutions.

At the very end I passed out a make-your-own-globe paper that I found here. I demonstrated to the class how to make the globe, using these directions:

1. Cut around the 12 segments (gores) that make up the globe. Cut right in between the gores so your scissors almost touch the equator (the line running through the middle) but don't cut all the way through!
2. Roll the cut-out into a cylinder and tape together both ends of the equator where they meet.
3. Take four pieces of tape, cross two, cross the other two, then cross the two sets (so you've created an asterisk of tape) and place it on the pointed end of one of the gores, so the sticky side faces upwards.
4. Bend the other 11 gores into the middle, so the tips meet at the same point.
5. Stick them down firmly on the tape. This end should now be cupped.
6. Do the same with the gores at the other end to create a sphere.


Don't be disappointed if your globe is not a perfect sphere. It is actually impossible to recreate a perfect sphere from a simple template like this! In fact, at the beginning of the lesson, I told the kids we were going to attempt two impossible things. The orange peel projection was the first, and creating a 3D sphere from a 2D sheet of paper is the second!

Have fun making your globes. :)

1 comment:

Anonymous said...

very smart method to explain on projection for (not only) kid...

good job!