http://www.bbc.co.uk/news/science-environment-12714225 Electronics miniaturization has advanced so far as of March 2011 that a PET scanner can be placed on the head of a rat, albeit with spring counter-weights, in order to measure the rat's brain activity while performing various tasks. What if by 2015 or 2020 a student might wear a PET cap the measures the student's activity while performing learning tasks? PET = positron emission tomography. PET scanners for humans historically have been very large and the human subject needed to remain completely still during the scan.