An effective teaching instructional facility is one which

An effective instructional aid activates all the senses, engaging the learner through multiple channels.

Being colourful and good looking is superficial and not the measure of effectiveness.

Being visible to all students is necessary but not sufficient by itself.

Being easy to prepare and use is convenient but does not define effectiveness.

The more senses an aid engages, the stronger the learning and retention.

This is why audio-visual aids outperform single-sense aids.