This is a familiar but underused teaching technique. When you invite students to role play, "The students' job is to shore up their friend, and they almost always bear testimony in the process -- almost without realizing it." (Becoming a Great Gospel Teacher, Eaton and Beecher, p 91)
"We've had our students play everything from missionaries to parents of troubled youth to concerned friends. The more realistic the situation, the better the exercise. It's best when student can dig deeply to explain and testify about gospel doctrines. Depending on the size of the class, we might first ask students to take turns role playing with each other and then try having one or tow students participate in role playing in front of the entire class.
Adapted from Becoming a Great Gospel Teacher, Eaton and Beecher, p 117