It
is significant that the student recognized this as task for which
setting up a proportion (a procedure she had learned) would be
appropriate. She makes a computational error and arrives at 2.5 as an
answer. She rejected this number after I asked to reflect on it.
She provides a reasonable estimate of the height of the new photograph
and seems happy with 20 as the computed height. She is unsure about the
additive method I propose, not rejecting it. However, she likes her
computed answer better. Her proportional reasoning in not well
developed.