When scheduling lessons in Teachworks you can click the "Check Conflicts" button to find if the lessons that you're scheduling have any conflicts.
Conflicts checked include:
Teacher Conflicts - Conflicts are displayed for the teacher's lessons, other events, unavailability, and hours outside of the availability set on their profile.
Location Conflicts - Location conflicts are shown for locations with the "Show Conflicts" setting enabled. Conflicts will be displayed if there are other lessons (excluding missed or cancelled) or other non-teaching events that use the same location.
Vehicle Conflicts - Vehicle conflicts are displayed if you have enabled the Vehicles add-on. Conflicts will be displayed for lessons using the same vehicle.