Obtain a ball (a childs smooth, bouncy, ball ~8-10 in diameterlike the ones you buy from the tall bins at discount stores). Write all 25 SM references randomly on the ball with a permanent marker. Begin by tossing the ball to a student. He catches the ball and then looks to see which references his thumbs are touching. He must then give the key words of the SM scripture (or quote the scripture) of one or the other reference that his thumbs are touching. He then passes the ball to another student.
A teacher shared the following [with John Bushman]: I found an idea that has worked REALLY well in my class and thought I would share. I was finding several of my students were lacking in their SM knowledge, even though we had been working on it every week. So I got a soccer ball. On the ball I have written the 25 key words. Every morning we have been tossing the ball around. When you catch the ball, whatever key words your right thumb lands on, the student says the keywords and then needs to say the reference. I have noticed the response time is quickened with the repetition!