Actions done for lower ability students:

• extra QnA session during free lesson or after school

• Extra tutorial time

• Simplified supplementary worksheet

• Provide extra aids for understanding (including youtube video and diagrams)

Actions done for higher ability students:

• provide question in advanced level

• Provide internal and external competition opportunities

• Individually explain some more difficult concepts

  
  

And use advance question/ video / online lesson with student having higher ability

Yes

Arrange supplementary classes for low archievers

Limited lesson time

The context of the school/students greatly influence on the decision making in solving the dilemma.

I think spending extra time after school works both ways, for weaker students or stronger students. Depending on the attention allocated during class time.

Personally I would still try to make more materials and put more effort, but my students are giving me negatives reinforcement and let's see how long this can go on