I need help, like an example

A developmental psychologist wants to study the effect of instructional type on recall of the alphabet. She randomly selects a sample of 20 students at the local preschool and assigns them to two groups, an "Individual" group who recites and practices the alphabet on their own using personal learning devices (n=10) and a "Group" group who studies the alphabet together (n=10). After one week of daily 30 minute sessions, all of the children are asked to recite the alphabet. The number of correctly recalled letters for each group are presented below.

Individual

Group

20

13

11

14

16

20

9

14

22

12

23

14

19

9

18

21

8

11

12

15