Karen described the connection of the two
activities by the nature of their consideration of
pH. She said that these two activities were
‘‘intended to familiarize students with the pH
scale, the use of indicators, and the formation of
acid solutions from dissolved gases’’. With no
prior instruction with the probes, she found that
the students ‘‘had a difficult time following the
procedures. From the errors they were making, I
feel that they did not really understand what they
were measuring with the pH probe’’.
Even though Karen indicated that the concept
of pH and the relative amounts of hydrogen and
hydroxide ions was ‘‘the real focus of the [first
lab]’’, she rejected the idea of extending the first
lab to an investigation of how these three
‘‘technologies’’ actually measured pH. This suggestion
actually fit within an investigation of pH
because of the three devices, the probe was the
technology designed to actually measure the
hydrogen ion concentration in the solution while
the other two technologies responded through
chemical changes resulting in the color differences.
She did not consider this extension to be within the
curriculum even though the methods and pedagogy
classes had emphasized incorporating a study
of technology and its relationship to science and
society. The chapter in the methods text by
Chiappetta and Koballa (2002) specifically suggested
that teachers should ‘‘explain how the
technology works and include the scientific principles
upon which it is based’’ (p. 135).