Must individual lessons that were not taught be made up, and is it permissible to call a single student to the home to make them up?

Contracts are the law of the contracting parties and their clauses must be adhered to, as Allah Almighty says: "Fulfill your obligations." If the contract was made for teaching specific classes during a certain period, then payment is due only for the agreed-upon teaching. If teaching becomes impossible due to a reason attributable to the school, then payment is due for the missed classes, as a private employee is entitled to their wage if they exert their effort and work becomes impossible due to the hirer. However, if the missing of classes is due to the teacher, then no payment is due, and they must return any received payment. It is not permissible to teach students at home to fulfill the obligation unless this is in agreement with the terms of the employment contract.