Characteristics of good teaching aids:

Teaching aids should be
Ø  Meaningful and purposeful
Ø  Motivates the learners
Ø  Accurate in every aspect
Ø  Simple and cheap
Ø  Improvised
Ø  Large in size
Ø  Up-to-date
Ø  Easily portable
According to intellectual level of students Sources of A.V.Aids:
Ø  Government
Ø  Educational institutions
Ø  Professional organizations
Ø  Non-governmental organizations
Ø  Voluntary organizations(national and international)
Ø  Commercial producers of educational material
Ø  Commercial advertisement
Ø  In nursing organizations like TNAI, INC...etc.