Geological Time Line Scale Mural

Geological Time Line Scale Mural

 

You know how there are some lessons that you do year after year, and there is something good about them, but you always sort of feel like the lesson isn't all that it could be?  Well, that's this lesson, and I think, maybe, this was a breakthrough year.

I'm always looking for ways to connect math to other areas.  A few years ago, I taught all of the subjects for 7th and 8th grade (science, social studies, 7th grade math, health, speech, and art).  Now, I don't teach the science any more, but there are a few lessons that I still really like.  

The Task:  Using a 6 foot long strip of paper, create a geological time line that is proportionally accurate (eons, eras and periods, although when we saw how small the periods got towards present day, we decided to just represent the eras and eons).  Then (the fun part), illustrate each.  

Background:  In previous years, I've given the task, set them off, and then we've laid them together at the end.  Inevitably, half didn't match up.  Some didn't even have accurately researched organisms.  

This year's modifications: 

• I extended the lesson plan for an additional two days (a four day plan).  We scheduled in multiple check points, and problem solved along the way.
• First, I gave students a "Math in Science" worksheet with a table with the estimated beginning years of each eon, era, and period with a few questions related to it.  We discussed scientific notation as a way to deal with big numbers.  For a few  students, this was already a stretch, and we spent a little while figuring out how to do scientific notation.  For a few students, I extended the lesson to show how to subtract or add using scientific notation.  We talked about how we could use this to figure out how many years were in each eon, era, and period.
• We talked about what kinds of things we might need to consider in working through this big task (and the many tasks within the Math in Science sheet as well), and hypothesized what kinds of math we might need.  We kept a running list on the board, and added to it each time we checked in. 

• Then, we reviewed how to use the percent proportion equation AND the cross multiplication method of solving proportions.  We did a few practice problems using both.  We also had to spend a bit of time making the the geological time scale analogous to a calendar.  We discussed our initial misgivings about how small the latest eon was compared with the other eons, and then looked back at the numbers and figured out why that was.  It took most students many tries to get the calendar correct.  Once I had a few students who were able to explain their thinking, they became math teachers as well, which freed me up to help other students who were struggling. 

 

• On the second day, I handed out the materials (measuring tape, 6 feet long register tape to practice on, 6 feet long butcher paper for the actual mural, meter/yard stick), and then I gave then a few minutes to talk about and start out their project.  It quickly became clear that many of them were planning on attempting to measure using customary measurements or had not quite understood the directions, so I called a group meeting to discuss points of interest. We added units as one of the things about which we'd have to take care. 

• I explained that we'd be comparing our data before beginning the artwork, and discussed how collaborating scientists and mathematicians need to agree on measurement units if they are going to compare their figures.  I told them we'd have to all agree on what units to use.  I asked, "What measurement units have you decided to use and why?"  The customary units groups explained that they had chosen their units because their paper was almost 6 feet long, exactly.  One group was using meters for similar reasons. Two groups were using centimeters because it would give them one whole number in the end.  One student pointed out that it's hard to use fractions with inches.  I allowed a few minutes to discuss and then asked them to decide on what units to use.  We agreed to use metric centimeters because it would make using proportions easier  (part to whole).   I think next year, we might go a little further into our choice on this, perhaps have a small reading on metric vs. customary and the merits of being literate in using metric.  
• Everyone had some more time to figure out where to put each period ending line.  At this point in time, the students' papers were still different sizes.  I didn't realize this.  They were figuring out where the periods would end, but their lines and numbers were not lining up with each other.  I thought their math was off, but when we reconvened, we realized we had to pick a common paper size if we wanted the end up with results that lined up consistently.  
• Once we decided on this, we went back to work, refiguring our proportions.  I made an impromptu table at the front of the class and asked groups to put their figures into the table when they had them.  We quickly realized there was another problem.  The data still wasn't lining up.  Some people were putting how long the period would be, whereas others were writing in where the line would be drawn, as measured from the end of the paper.  Some people were rounding up, others not at all.  We went back into discussion and decided that we'd round to nearest whole number and only put in the measurement of the mark from the end.  (More re-figuring of data.)  

• Once our table was consistent, we went to measuring out the lines on our practice sheet.  Once completed, these were taped to a table, lined up next to others.  We saw that some still didn't match, so we had to remeasure while all together, and then mark the agreement line on all of them.  

• Once we agreed on where the lines should be, the students used that practice sheet to make their lines on their bigger project.  Then, they researched the periods/eras/eons and took notes on what they wanted to draw in each sections of their mural.

• Finally, the fun part (for them)... they worked as a group to illustrate the geological time line using colored pencils and permanent markers.  We used the John Kryk interactive AND the BBC History of Life interactive and mini-documentaries as our main research tools.  Next year, we're going to add in the Deep Time website, and we will discuss making the geological time scale proportional to a clock as well.  (My co-teacher, Anna, shared this awesome resource with me.)

• The final result is beautiful.  A few of the illustrations are not entirely accurate, either due to resorting, at the last minute to google images or just to little misunderstandings, but overall, I am pleased with the math they did to accomplish this project, and the number of steps we had to take along the way.