There is abundant material throughout the book illustrating the changes
in root words when derivatives are formed. This does not mean, however,
that there is nothing for the teacher to do. The teacher must keep
constantly in mind that it is not necessarily true that because the
child can spell “health,” he can spell “healthy.” Below is given a list
of twenty-three words and one or more derivatives which were given to
approximately 1,000 children in the sixth grade. It was known beforehand
that the root word had been taught either during the year or in the
fifth grade. The number following each word indicates the percentage of
accuracy with which each word was spelled. It will be noted that in each
case the root word was spelled with from 5% to 40% higher accuracy than
the derivatives.