Thank you for your inquiry regarding usage of rests in 7/8 time, and specifically the examples on pg. 64 in Celebrate Theory, Level 8 Theory.

Your observation that students are instructed not combine beats 2 and 3, which are both weak, in compound time is correct. However in repertoire using hybrid meters such as 7/8, there are often situations that “break the rules.”

In Celebrate Theory, Level 8 Theory, on pg. 59, a number of groupings are demonstrated, including 2+2+3, 2+3+2, or 3+2+2. These examples demonstrate the conventional groupings, but are not exhaustive. The example on pg. 64 shows a situation in which the half rest combines a weak beat with a weak beat that follows. While in simple or compound meter, this would be unacceptable, within hybrid meters it might occur in repertoire.

For examination purposes, we do encourage students to follow the conventional groupings shown on pg. 59.