When playing Copycat or Call and Answer, a complicated end to the rhythm often causes a student to miss their entrance. To focus on the challenge of listening while preparing for their entrance, play copycat rhythms that include the "1", and increasingly complicated hits in the "3" and "4" counts. For example,
D--- ---- ---- D-D-D--- ---- ---- --D-D--- ---- DKKD KDDKD--- ---- --D- KD-K
etc.
The students' priority is to hit the "1", even as their brains are still processing the complicated ending. They should try and catch the ending as well, but that's less important than not losing the beat.
Check that students' right hand is raising up well in time to prepare for the "1". You can explain that the moment they hear you play the "1", they might as well get that hand up and wait in the up position. Practice this specific skill with challenge patterns that include and omit the "1". For example,
D--- ---- D--- ---- (students should raise right arm in prep)---- D--- ---- ---- (no raise)---- ---- D-D- D-D- (no raise)D--- D--- ---- D--- (raise)
etc.
This drill is well suited to students of different levels. Struggling beginners can simply ignore the complicated ends of the phrases and more advanced players can try and catch the whole phrase.