One of my first jobs had in-service workshops every other Saturday. Yes, people would complain that they would have to go to unpaid training, however, it really helped everyone involved. Two teachers were chosen at a time to present about a specific topic. By doing this, everyone got to present as well as be part of the audience. Learning about new topics and methodology is what teaching is all about since these things change often.
External workshops and conferences
I'm surprised at how few places encourage teachers to go to workshops and conferences. At the very least they should let teachers know about upcoming events. It would be nice if they would also offer to pay for part of the entrance fee.
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Observing other teachers and being observed can help teachers learn new ways of teaching and get feedback on how they teach. The school should set up times when teachers can be observed.
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