Student or Learner
I am wondering if I have written this sentence correctly. Would you please correct my mistakes?
1. When John moved to another school he became more disciplined than before.
I am wondering if I need to add "than he was before" like in the following sentence:
2. When John moved to another school he became more disciplined than he was before.
"he was" is not required in your sentence. In fact, as long as the meaning is clear, you don't even need "than before".
When John moved to another school, he became more disciplined.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.