Proving in school geometry is not just about validating the truth of a
claim. In the school setting, the main function of the proof is to convince
someone that a claim is true by providing an explanation. Students
consider proving to be difficult; in fact, they find the very concept of
proof demanding. Proving a claim in planar geometry involves several
processes, the most salient being visual observation and deductive argumentation.
These two processes are interwoven, but often poor observation
hinders deductive argumentation. In the present article, we
consider the possibility of overcoming the obstacle of a student’s poor
observation by making use of computer-aided observation with appropriate
software. We present the results of two small-scale research
projects, both of which indicate that students are able to work out considerably
more deductions if computer-aided observation is used. Not
all students use computer-aided observation effectively in proving tasks:
some find an exhaustive computer-provided list of properties confusing
and are not able to choose the properties that are relevant to the task.
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