Is it permissible for me to perform tayammum to pray at school if the principal prevents me from performing wudu, knowing that I can pray at home, but I desire to pray in congregation and to perform the prayer on time?

Tayammum (definition) is not permissible except when the use of water is impossible due to its absence, or due to fear of harm from its use, as Allah Almighty says: (and find no water, then perform tayammum with clean earth) and His saying: (And if you are ill). Tayammum requires conditions, including: intention, Islam, sanity, discernment, istinja (definition)' (cleaning oneself after relieving oneself), the entry of the prayer time, the impossibility of using water, and that it be with pure earth. Therefore, the presence of water and the absence of harm from its use do not permit tayammum. The school principal preventing ablution is not an excuse that permits tayammum. Rather, you should perform the prayer when you return home. It is advisable to advise the principal or complain about him if he does not respond. It is also possible to perform ablution inside the restroom.