Set up a role play to act out a study or theory. Allocate specific roles within the group and ask the group to write a script including props they might need to act out their play.  The group presents their play to the rest of the class who might rate them on how good their  play is. The play should demonstrate the key points of the topic. Those students who are not confident in acting can contribute to the group by writing the script, making props and directing the play. If role plays are especially good, consider filming them and putting onto youtube for other students to use.