They can also be used to provide feedback to student assignments and is a very useful medium to check student pronunciation when teaching languages at a distance. Audiocassettes can be an excellent supplementary medium to enrich print or other media and can provide resource material to distance learners. Since they can be produced and distributed without much cost, audiocassettes are also a very cost-effective medium for use in distance education. Videocassettes Videocassettes are like broadcast television in that they combine moving pictures and sound but unlike broadcast television are distributed differently and viewed in different ways. Videocassettes are also a very flexible medium allowing students to use the cassettes at a time that is suitable to them.
Students can repeat the material until they gain mastery of it by reflecting on and analyzing it.
The control features that videocassettes afford the learner give course designers the ability to integrate video material more closely with other learning materials, so that learners can move between lesson material supplied by different media. The ability to create 'chunks' of learning material, or to edit and reconstruct video material, can help develop a more questioning approach to the presentation of video material. In e-mail systems a message is routed by the system to the addressee's mailbox on the host computer and remain there till it is read by the addressee. This message can be read, replied to, left in the mailbox for later perusal, saved to the hard disk on the microcomputer, deleted, or forwarded to someone else. Most e-mail systems have a bulletin board feature which allows users to read and post messages and documents to be seen by all.