Need help for a SQL query to see if teacher is double booked for classes

Here is the constraint:

 Check if a teacher is scheduled for back-to-back classes (two adjacent class periods). Some teachers are ok with this but we like to double check early.

In the table, there is a Time Begin, and a TIme End for classes

Back to back classes example would be: 11:00 - 12:15, then 12:30-1:45