You should know that most private schools are not after who knows it most. So don't worry yourself for not being considered in that interview. Most proprietors need those who can meet their demands, so they always surround themselves with people that will stroke up their ego as they need occasional blandishment.
Below are some reasons why you did not get that teaching job even after putting up an excellent performance:

1. Most external exam officers are not immune from bribery: What a travesty of education! This particular trend has contributed to the negligence of those teachers that are experienced enough. This is because criminal-minded exam officers collect bribe from schools and open way for exam malpractice. The proprietors who rely on such exam officers don't care if you finished first class. To them anybody can do it provided the right answer is supplied to the students during exams.

2. Fear of your threatening profile: Opportunities are always open for experienced and brilliant teachers. This has made proprietors to doubt the durability of such teachers. Fear of short stay which parents always complain about may cause the rejection of the best performers in an interview.

3. Laissez faire attitude of TRCN: Despite the public's cries for TRCN investigation into the trends in Nigerian education, the body's response has been slow and piecemeal at best. Suffice it to say that correcting the 'all comers affair' syndrome that most proprietors have branded teaching is not the major thrust of the Teachers' Ruling Council of Nigeria (TRCN). This body has not been doing its primary duties which is separating 'made' teachers from 'born' teachers. This negligence has empowered many proprietors to throw open teaching to every Dick, Tom and Harry. You know what that mean. Those who the owner choose are the one they employ irrespective of their execrable performance.

4. Your rectitude of moral: If you quibble on moral ground during your interview, some proprietors may be worried on how you can cooperate when it comes to number one above. Don't forget that teachers are allowed to conduct exams alongside WAEC/NECO exam officers. Those who are on duty with the exam officers are the ones to supply the 'expo' and you that is the subject master will be the one to prepare the 'expo'. They will ask you some tricky questions to test if you can partake in such shady deal. Such question cannot be direct but it is known with the popular bible verse that says "by their fruit we shall know them". You know you must exude confidence if you hope to succeed in an interview and you cannot do it without saying whom you are. When you are faced with an ethical dilemma of either lying or saying the truth, if you are the upright type you will always go for the former. So your ingenuous habit of constantly telling the truth can deny you that job if the proprietor is the type that hates truth.