OHP stands for Overhead Projector. This is a device for displaying a page from a book or a transparency enlarged on a wall for all the class to see. These days it has largely been replaced by interactive whiteboards although many schools still employ their use, especially in less developed countries.
Overall the OHP is a good teaching tool but it needs to be used well, and teachers must be careful not to rely too heavily on it.
Here are some issues teachers, experienced and inexperienced, should be aware of:
- Discipline can be a problem in a darkened room and sometimes the classroom can become “a sleep zone”. To avoid this, keep use of the OHP short and to the point and make sure you interact with the class while using it.
- In the absence of a screen, many teachers use the wall. if the wall is dirty or painted in a dark color it becomes virtually impossible to see the transparency. To avoid this, plan in advance where you’ll project and make sure it’s suitable.
- Some teachers doodle on the transparencies instead of planning the use of the whiteboard in conjunction with the OHP. To avoid this, plan your lesson and the transparencies well.
- The OHP can limit the opportunity for class discussion. To avoid this, stop frequently and invite student comment and discussion.
- The use of the OHP can make students lazy with information written for them and they take notes. Students tend to write more if the teacher is writing the information on the board as it’s discussed.
- Teachers can become too reliant on pre-planned lessons not allowing for flexibility and variety.
- It is important to avoid information overload. Too many transparencies or too much information included on each transparency can mean too much information for students. Keep them brief.
- Note-taking can be difficult in a darkened room. Stop frequently and turn on the light to allow notes to be written.
In general then one can say OHPs should be used in short bursts and sparingly.