Unit 1 Reflections: Comparing Volume Units (Part 1)

I think I figured out my "mistake" this semester that left my students struggling with the concept of particles.  Part of the problem is they have low retention from their previous science courses, but I think next time around, I will re-order the lessons a bit.  I made the assumption that students understood that matter is everything, and that matter was made of atoms (or particles).  I think I need to review that in greater depth next year before jumping in to mass.  Dot in a box would be a good part of the pre-lab discussion for the Mass & Change lab.  Upon seeing their poor grades on Worksheet #1, students seem to be finally coming around to the idea that particles are important and they actually have to pay attention when they draw them.

My students proved me wrong today.  Or shall I say, most of my students proved me wrong today.  I expected them to struggle badly with the Comparing Volume Units lab.  The majority of them did not struggle at all.

For this lab, I ordered a set of the Giant Geo Solids from Nasco, as the lesson plan suggests:

I actually bought them with my personal money, since my school's science department is currently operating in the red.  I knew I would get flack about ordering expensive plastic containers, so I just sucked it up and bought them myself.

If anyone is out there reading this, do not bother ordering the Giant Geo Solids, or at least be forewarned that it is a lot of wasted money.  Half of the items in this kit are useless for this lab.  The problem is that the recommended kit includes 10 different shapes; 2 of them are hemispheres and 3 are pyramids.  Do they really expect the students to find the volume of different heights of water in a closed cone, hemisphere, or pyramid with the opening in the base?   That is unnecessarily difficult.  So for over $70, I only received 5 containers I can actually use for this lab.  Luckily, I have reasonably sized classes this semester and could get away with 5 groups.  But it would have been a better use of my money to try and find some sort of clear plastic geometric container at Walmart-- someone has to make something useable that is sold in the toy, floral, or storage departments.

With pre-lab, we revisited the phrase "matter is anything that has mass and takes up space."  I told them that we already discussed mass and how changing the number of particles affects the mass.  So how do we measure taking up space?  (Volume)  How do we calculate volume in geometry class?  (LxWxH or area x H)  What are the units for volume?  (cm3)  Then I pulled out a bottle of water and asked them how to calculate the volume of a liquid, pouring a bit on the floor to make a puddle.  I asked if they could calculate LxWxH of the puddle (no, it spreads).  So how do we measure volume of a liquid?  (graduated cylinder)  What units are on a graduated cylinder?  (mL)  Why are the volume units for a solid different than the volume units for a liquid?

Then I gave them the purpose of the lab:  To determine if there is a relationship between cm3 and mL.  Their only directions were, "Determine the mL and cm3 of 5 different heights of water in your container."

Lucky groups got cubes or rectangular prisms

One unlucky group got a hexagonal prism.  I was surprised when one of my students knew the formula for area of a hexagon without looking it up!  He informed me he was currently in geometry for the third time, since he failed it twice.

The majority of my students breezed through the calculations with little help from me.  I was impressed.  Then, I had students draw a graph of mL vs. cm3 in their lab notebooks and calculate the slope of the line.  I did give them guidelines of putting mL on the X axis and cm3 on the Y axis.  They had minimal difficulty with this task as well.  The lesson plans suggest using Vernier for graphing this activity's data.  As I've mentioned before, we don't have Vernier equipment at my school.  I have my own copy of the software, but it's not installed on our school's laptops.

That's as far as we got today, since we had spent the beginning of the class period going over their previous night's homework (extra histogram practice).  Tomorrow we will white board...

We are so far behind.  I need to figure out what I can cut from unit 1.  I'm thinking of cutting the thickness of tin foil activity.  While it's cool they can determine the relative size of an atom, I think it's not the best use of our time...