Possible Clues:

• Masters them to get inside the rust
• Private teachers for students
• Teachers of individuals or small groups
• Teachers, usually of individual students rather than classes
• After-class coaches
• It's a bit fishy when trout's teach lessons at university
• Homework helpers
• Teaches one-on-one
• Expression of annoyance initially over red socks and trainers
• Teachers make disapproving sound or shout at the front