Singh, Gurinder and Haydock, Karen
(2016)
Let students ask and investigate: the case of a variegated plant.
I wonder (2).
pp. 71-76.
Abstract
who asks most of the questions in a
classroom - students or the teacher? In
many cases, it is the teacher who does most
of the questioning. And what kind of questions does a
teacher ask? Questions for which the teacher already
knows the answers! Students in schools are trained to
give these answers, and are assessed for their ability
to do so. Even if they do ask questions, students are
expected to only ask ‘textbook’ questions that lie
within their school curriculum. An activity which is sometimes done in school in
order “to prove that chlorophyll is required for
photosynthesis” is to take a variegated leaf, remove
its green pigment by dissolving it in alcohol, and
show that only the areas which were formerly green
test positive for starch. However, this is a rather
tedious procedure, and it actually does not prove that
chlorophyll is required for photosynthesis, or even
that photosynthesis is occurring. It merely indicates
that only the green areas contain starch. It may even
lead students to ask questions like, “Why does a
potato, which is not green - also contain starch?” Is the
potato also capable of carrying out photosynthesis?
We can also question whether starch is an indicator of
photosynthesis.
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