A psychologist has developed a set of activities which she hopes will help children develop better reading skills. In a study of the effectiveness of these activities, one class of second grade children learns with the activities. Another class of second grade children serves as the control, and learned without the activities. After some period of time, the reading skills of all of these children were assessed. A summary of these data is:

S Activities class: 21 51.48 11.01 No Activities class: 23 41.52 17.15