A study of computer-assisted learnng examined the learnng of "Blissymbols"
by children.  Blissymbols are pictographs that are sometimes used to help
learning-impaired children communicate.  The researcher designed two
computer lessions that taught the same content using the same examples.
One lesson required the children to interact with the material, while in
the other, the children controlled only the pace of the lesson.  Call these
two styles "Active" and "Passive."  After the lesson, the computer presented
a quiz that asked the children to identify 56 Blissymbols.  The dataset 
contains the numbers of correct identifications by 24 children in the Active
group and 24 children in the Passive group.  The variables are:

group -- "A" for Active, "P" for Passive
score -- number of correct identifications