As the inquiry progressed, Don again took the initiative to use
his notebook independent of assistance. During a period of
sharing, Don tried to explain to the class his thinking about
the importance of bubbles in the system. He stated that, “Also
what I noticed too, sometimes when you press up the water
goes up and sometimes there are small bubbles on the
bottom.” He then drew a version of the CDS on the board and
added, “What I figured out is that when water gets pressed
there are bubbles sticking to the bottom of the balloon.”
When two students said they hadn’t observed this, Don
advised that “They are very small.” Later, the students had
time to write in their lab books, and Don wrote, “it thars in
to little BoBd Sum air stas in the Diver and gets smaler” and
depicted two versions of the Australian CDS, one with and
one without bubbles (see Figure 5).