I found this lesson by Robert Kaplinsky and was excited to use it to teach scientific notation to my eighth graders. I have a class of 13 students and a class of 38 students (with two aides). I wasn't sure if I could pull off the same lesson in both classes, but thought I'd give it a try. I also found this lesson from the Shell Center that I thought would tie in nicely, and an online app called Scale of the Universe.
We do Andrew Stadel's Estimation 180 every day in class, and I thought that the question for today's lesson would substitute nicely for our usual routine. I had students make a high and low estimate and their best estimate. We had some great conversations around astronomy, including whether the size of the universe, how light travels, and how stars are born and die. Some of my students had a lot more knowledge about these things than I knew. I wasn't expecting students to ask how we take into account the fact that stars are being born and dying all the time, or whether we should count the stars that have died, but we still see them because their light is still traveling to us. Or the stars that are exist, but we don't see them because their light hasn't made it to us yet. I also didn't really know how to answer the question about the size of the universe. Many students said it is infinite, but I thought that the universe has a boundary but is expanding. Correct me if I'm wrong.
I had to do some work to get students to think about how we could estimate the number of stars in the universe by multiplying the number of stars in or galaxy by the number of galaxies in our universe. Many students said that galaxies are different sizes and contains different amount of stars, so we wouldn't get a very good estimate. I asked them to consider whether we could come up with an average of the number of stars in each galaxy and use that in our estimate. I don't think every student agreed with this strategy of estimating the number of stars in the universe, and many still thought the task is impossible.
However, once I showed the video on the number of stars in a galaxy and the number of galaxies in the universe and had students work on multiplying the two numbers, they did some great work. We had to review how to write 100 billion and 400 billion in decimal notation. Many students used their phones and came up with 4e+22. Some got 2x10^22 on their calculators. Very few thought to add the zeros on 100 billion and 400 billion. I had students write the different representations on the board, including 4 followed by 22 zeros. We talked about what 4e+22 means because I think it's important for students to be able to interpret what their calculator is telling them. At this point, a student suddenly raised her and said, This is sci--- sci--- scientific notation. I was so excited that someone recognized it!
After talking about the solution, we practiced writing numbers in scientific notation. Then students worked on a modified activity from the Shell Center. I turned their activity that has students matching cards into a worksheet because I didn't think my classes could handle the matching activity, especially the class of 38 students. In the smaller class we had time for students to match the objects to the measurements, but in the larger class we're saving it for Monday.
After doing the worksheet, I showed the Scale of Our Universe. It's really great for this lesson because it shows the scale in scientific notation. It also peaks kids' curiosity. I started by zooming way out to see galaxies and other objects in the universe, and then I zoomed way in. Kids had a lot of questions and thoughts, which was great to see.
I was surprised that this lesson worked well for both of my classes, even with how different they are. Some students wanted to know why we were learning about science in math class. I hope they see that math is not a self-contained subject, but it touches on many other subjects. That's something I need to work on expressing and demonstrating to students.
Here's the powerpoint I created to present the lesson, as well as the worksheet I created from the Shell Center activity, in DropBox.
