Density Lab: ELD/SDC Day 2- Cartesian Diver

Today the students worked together on white boards to do 3 things with the Cartesian Divers: Scientific Diagrams, Observations and Questions. I had tro use eyedroppers instead of ketchup packets because the ones that I had gotten only one of them floated. 
First, I introduced the Cartesian Diver and how it worked.  Then, we split the white board into 3 sections. A top section for the picture and a T-chart below to record observations and questions.  I listed the materials on the board and show them what each one was: water, eyedropper and 2-liter bottle.
Their goal was to draw and label the cartesian diver, and have 3-5 observations and questions. I told them to play with the cartesian diver. 
We had to work on the words: squeeze, up, down, and water level.  We also worked on their oral language. Using beginning stems like: I see...and I made them say it in a full sentence correctly before writing it down.

• the eyedropper go up and down when I squeeze the bottle
• bubbles on the eye dropper.
• the water in the eye dropper go up when the eye dropper goes down
• the eye dropper was jumping
• the bottom of the eye dropper there is a bubble
• when you tap the bubble it goes up very fast

Questions that students came up were interesting-

• Why is there a bubble in the eye dropper?
• What happens if the water is hot?
• What happens if there is more air?
• Why does the top of the eye dropper stick out?
• *Why does the eye dropper go up and down?
• Would the eye dropper go to the top if the cap was off?

* more than half the groups had this question

Just one more note- my backroom was cold and the classroom was warm about 72 degrees.  By the time I moved the Cartesian divers to the warm room the divers had sunk to the bottom of the bottle.  I thought I was doomed until I thought about it and I opened the closed system. It all equalized so the eye droppers floated to the top again. The students noticed, but I did not provide any explanation to it.  Only one group wrote down that observation on their white board.