It is possible to divide the attention but then it can not be of
the highest quality. Try the experiment of doing a simple problem
in arithmetic and at the same time say a familiar verse, as
"Humpty-Dumpty." Again try to write the lines of "Mary had a little
lamb," while you say aloud the lines of "Humpty-Dumpty." While you did
succeed in doing the first you do not succeed in doing the second. This
experiment should be tried by all children to show them the effect of
dividing the attention and of how it may be done when necessary, but
only to a certain degree. The difficulty of the verse and problem can
be accommodated to the age of the child.
The attention may be divided between two objects or acts if they call
for the use of two different senses or are different in their order.
You can not divide your attention between two acts of the same order,
as two arithmetic problems, one mental and the other written, or
between two operations of the same sense. You can not listen to two
quartets singing at the same time, but you can attend to one and smell
some flowers at the same time and do both fairly well. While using one
of the senses for fixed attention train the others to relax.