Offer extra challenges to the high performing students who are willing to help tutor the lower performing - then both groups benefit. Tutoring/mentoring in a field is the fastest way to consolidate learning and stimulate new ideas. Having to explain something to someone else makes sure you understand it yourself - it is never time wasted.

What can be done to keep engage high performing students while attending the low performing students in the class room?

Suggesting following 2 approaches:

One interesting n time consuming problem in a class will definitely engage brighter student's.

Many thanks to you all.