There is a training room that you can assign 4 people to train (teaching-management-research) and there is the headmaster office that gives you 1 training slot.
Training increase their skill to around their potential (the glasses symbol) and skills cannot be earned with training instead skills are earned by putting staff members in specific positions (management position gives management certificate, assigning to school store gives service certificate,etc.) So training do not give skills(certificates) but make them manage more things or teach higher requirement classes or research faster.
There are training limits, look at the stats with glasses. They cannot train beyond that,
Teachers can increase their stats throughout the year. Just because the prediction that everyone will fail is there, doesn’t mean it is true. I have not built the training room and have been churning out consistent “full mark” classes after my 2nd group of graduates. By then, you will ideally have pairs of teachers to guide students throughout the three cycles with you.
The training is good for immediate short fixes, such as your teacher’s stats being single digit when you need someone in the tens. From experience, anything beyond 15, takes too long for the immediate issue I need to fix. At times, you may be better off just hiring teachers with appropriate stats.
The tutorial fails to mention that from 1st week to 3rd week you are in a rat race to get your Intermediate Course Work for both Humanities and Science done, after that it depends on how you want to grow. Personally, I kept to Humanities and Science and beefed up the education for it. My third year regular students have 4x as much as the minimum scoring for their exams.
Stat wise, anything beyond 25 is more than enough, except for the extreme problem students.
A homeroom teacher between 15-20 management is a very good start.
A teacher with similar teaching stats the same. That should be more than enough for your 10-15 student classes.
What you need to churn out is research, 3 researches should get you to making that 3 week time hack in having the education requirement met. If you have cash to burn, train the researchers more before they get their certs. You can use the chief researchers later to be a department manager, if you can’t find one through the talent marketplace.