Make worksheets and have the keyboarding kids color in the letters/keys they are working on or color the entire board with various colors to indicate different categories. Also make blank keyboards that they have to fill in by writing the correct letters, numbers, and symbols.
Check out Dance Mat Typing for a free online typing program. Dance Mat Typing provides free touch typing lessons appropriate for children ages 7-11. There are four levels each comprised of three stages. There are also free typing worksheets available to print and use offline.