Density Lab Day 3: Layering 2 liquids at a time

Fig 1

The students were given 4 test tubes (in a rack) and a test tube brush (fig 1).  I had the 4 liquids on the front counter and had them come up and get them when the lab started.  

I told the students to pour the liquids in the test tubes, 2 at a time and record how they layered (Fig. 3).  As the day went on I stressed being careful of the pouring and I even gave them a tip on how to pour the green liquid (hold the TT verticle and pour slowly from 5-10cm above the TT)

Fig. 2

The alcohol and the water layered nicely (Fig 3) IF the students poured carefully and IF they pour the water first.  I discussed why briefly.

Fig. 3 Water and the alcohol

P3,5 &6 I did not have them predict, because it encouraged the misconception that the order you pour them affects the layering and I structured their data table more (told them what I wanted to see in it)