Density Unit Day 8: Mystery Liquids

Fig. 1

  I got 2 new solutions (see fig. 1):

• Salt water (dyed Black, although it looks green) - made by heating 1000ml water in the microwave, adding a TON of salt, and mixing until all the salt is gone that is going to be gone, then pouring it into another container, leaving the salt behind.
• Baby Oil (not dyed, left clear)- bought at CVS

I told the students that they needed to determine where the new liquids would fit into the existing layers.  In order to do this they need correct numbers form the previous lab.  I had some of the liquids out for students to redo or finish that lab.

Period 1 I left it relativity open, I said that all I wanted was a Claim (about where the clear and the Black  would fit into the layers) and Evidence (using numbers).  Most everyone started to make a data table right off the bat, and I have very little problems.  2 groups misunderstood the directions and simply stated how the clear and the black would layer. almost everyone finished and got stamped.

Period 2 I gave them a little more structure in that I had them write "Claim" and "Evidence" on their paper, and I said that I wanted a data table (I think?).  Some put the data table below their Claim And evidence, while others added on to their data table form the previous activity.  Some just wrote their data at the bottom in no table, but provided data in their claim. almost everyone finished and got stamped

Period 3 I gave them given more structure, in that I said that I wanted them to have a data table at the bottom. Most finished and got stamped.

Issues:  There needs to be something for the students to do.  some students are breezing right through this and then they are done.  others are still struggling with the lab from the day before (which they need) and it takes them longer.  The students that are done have nothing to do (which could mean problems).

NOTE: the baby did not float on alcohol (did we think it would?) not a huge issue.

Tomorrow I plan 2 things, 1)demo the placing of the 2 liquids, and 2)give them a list of the known densities for the liquids (plus some others) and have them try to guess the liquids.