Visual aids are the tools of teaching through the sense of sight. They are supporting materials & they alone cannot generate learning. They should be considered only a tool that helps to do a job in a better way.
Visual aids are of different types. The following are the more commonly used ones in India:

1. Posters
2. Flannel-graphs
3. Flash cards
4. Puppets
5. Slides & film-strips
6. Models
7. Bulletin boards
8. photographs
9. Black-boards
10. Cultural programmes

Posters. A good poster creates awareness & interest among the people. It inspires & takes people towards action. It consists of 3 main parts. The first usually announces the purpose or the approach, the second sets out conditions, & the third recommends action. A poster should be bold enough to attract attention of the people, & should communicate only one idea at a time. It should have simple letters which are clear & forceful. The size of a poster should not be less than 50*75 cm.
Flannel-graphs. Flannel-graphs serve as a good teaching aid. When a piece of sandpaper is fixed to the back of a picture, a photograph, a letter, etc. They can be made to adhere easily to a piece of thick flannel cloth, fixed on a board. They are used as an aid for group methods like informal talks or lectures.
Flash cards. Flash cards are a set of small compact cards approximately 30 to 45 cm. In size, & are used to bring home an idea, such as the benefits of a smokeless chulha, the cultivation of hybrid maize, compost-making & other practices. Pictures on the theme are drawn on these cards in a logical sequence which are flashed before the audience. Upon seeing them, the villagers are able to follow a story more easily.
Puppets. Puppets are very popular & especially suitable for village situations. Puppet shows can be effectively organised to gather the rural people. For a puppet show, a short story, brief scenes & quick dialogues are necessary. Such shows can teach a lesson about health, literacy, agriculture. Or home-making.
Slides. A slide is a transparent picture or photograph in an individual mount. For viewing the image, the picture is projected through a slide-projector which brings the enlarged image into focus on a screen. Slides are excellent aids of illustrating talks & showing people concrete activities & aspects of development. They can be effectively used to show different situations & methods of carrying out an activity. They can be arranged in a series for giving an illustrated talk on improved agricultural practices, cultivation of crops, etc.
Film-strips. They are a series of black-and-white or coloured pictures depicting a single idea, & instead of being individually mounted are printed on a single length of strip of 35-mm film. Such strips can be shown to an audience of about a 100 people. The additional advantage in using the film-strips is that the film can be stopped anytime during the show to explain or discuss a difficult or interesting point.
Models. Models create a sense of realisation in a person. Models of new farm equipments, compost pits & sanitation devices & animals are mostly prepared for those people who are not in a position to see them in the actual form. They are used to create interest, promote understanding & influence the people to adopt a certain practice.
Bulletin-boards. A bulletin-board can serve the purpose of making announcements, displaying events of short duration & photographs of local activities. The information should be written in simple language.
Photographs. They are a very simple visual aid. Good photographs show some action & catch the feelings & emotions of the people. They are so arranged that they tell a story. They are displayed on a bulletin-board at a common meeting-place where a large number of people can see them. They should be clear & bold in composition with proper captions.
Black-boards. They provide a writing & drawing surface for chalk. They are usually used in schools, colleges & meeting places. They make possible the use of sketches, drawings, words, symbols of a combination of them to emphasise a point. Black-boards are most useful in group-teaching methods.
Cultural programmes. Local cultural programmes, such as folk-songs & dramas, are used as an effective medium of communicating the message of development programmes. Dramatization of a theme or story creates a lively interest among the audience. Folk-songs & dances related to the subjects of local interest & importance, when acted on the stage, bring them home more forcefully.

For an effective use of extension-teaching methods, it is not enough to know these methods & their techniques. What is more important is the appropriate selection of a method or combination of methods for a particular situation. In fact, when a farmer is exposed to a new idea several times by different methods or a combination of methods, he is likely to accept it more quickly. Farmers learn about new practices through several stages. These stages are known as: (1) the awareness stage- when a person comes to know of a new practice but lacks the complete information; (2) the interest stage- when he becomes interested in a new idea & wants to know more about it; (3) the evaluation stage- when he mentally applies the new idea to his present situation & evaluates it; (4) the trial stage- when he applies the new idea or practice on a small scale in order to determine its utility under his own situation; and (5) adoption stage- when he decides to continue the full use of the practice. Thus, it is the cumulative effect on people through exposure to an idea repeatedly that results in action.

Programme-planning. The first step in any systematic attempt to promote rural development is to prepare useful programmes based on peoples needs. The development of such programmes, which harmonize with the local needs as the people see them & with the national interests with which the country as a whole is concerned, is an important responsibility of extension personnel at all levels-national,state,district,block & village.
Programme planning is the process of making decisions about the direction & intensity of extension-education efforts of extension-service to bring about social, economic & technological changes.

Principle of extension programme-planning. The planning of an extension programme is done on the basis of certain well recognised principles which should be clearly understood & followed by extension workers. The main principles are:

1. The programme-planning should be based upon a careful analysis of a factual situation.
2. In a good programme-planning, problems for action are selected on the basis of recognised needs.
3. A good programme-planning determines objectives & solutions which are feasible & offer satisfaction.
4. The programme should be permanent & flexible to meet a long-term situation, short-time changes, & emergencies.
5. A sound programme should have both balance & emphasis.
6. A good programme has a definite plan of work.
7. Programme-planning is a continuous process.
8. Programme-planning is a co-ordinating process.
9. Programme-planning should be educational & directed towards bringing about improvement in the ability of the people to solve their own problems individually and collectively.
10. A good programme-planning provides for the evaluation of results.

The programme-planning process. The steps involved in this process are as follows:
1. Collection of facts. Sound plans are based on availability of relevant & reliable facts. This includes facts about the village people, physical conditions, existing farm & home practices, trends & outlook. Besides, other facts about customs, traditions, rural institutions, peoples' organisations operating in the area, etc. should be collected. The tools & techniques for collecting data include systematic observations, a questionnaire, interviews & surveys, existing governmental records, census reports, reports of the Planning Commission, Central Bureau of Statistics, & the past experiences of people.
2. Analysis of the situation. after collecting facts, they are analysed & interpreted to find out the problems & needs of the people.
3. Identification of problems. As a result of the analysis of facts the important gaps between 'what is' & 'what should be' are identified & the problems leading to such a situation are located. These gaps represent the peoples needs.
4. Determination of objectives. Once the needs & problems of the people have been identified, they are stated in terms of objectives & goals. The objectives represent a forecast of the changes in the behaviour of the people & the situation to be brought about. The objectives may be long-term as well as short-term, & must be stated clearly.
5. Developing the plan of work. In order to achieve the stated objectives & goals, the means & methods attaining each objective are selected & the action plan, i.e. the calendar of activities is developed. It includes the technical content, who should do what, & the time-limit within the work will be completed. The plan of work may be seasonal, short-term, annual or long-term.
6. Execution of the plan of work. Once the action plan has been developed, arrangement for supplying the necessary inputs, credits, teaching aids, extension literature etc. has to be made & the specific action has to be initiated. The execution of the plan of work is to be done through extension methods for stimulating individuals & groups to think, act & participate effectively. People should be involved at every step to ensure the success of the programme.
7. Evaluation. It is done to measure the degree of success of the programme in terms of the objectives & goals set forth. This is basically done to determine the changes in the behaviour of the people as a result of the extension programme. The evaluation is done not only of the physical achievements but also of the methods & techniques used & of the other steps in the programme-planning process, so that the strong & weak points may be identified & necessary changes made.
8. Reconsideration. The systematic & periodic evaluation of the programme will reveal the weak & strong points of the programme. Based on these points the programme is reconsidered & the necessary adjustments & changes are made in order to make it more meaningful & sound.

Programme-planning is not the end-product of extension activities but it is an educational tool for helping people to identify their own problems & make timely & judicious decisions.
From the above mentioned cycle, it is clear that the planning of an extension programme comprises a logical series of consecutive steps. The first 4 steps form the programme-phase. The steps 5-7 form the action-phase. The step 8, i.e. reconsideration, joins the 2 phases together, where it leads to the fact-collecting step, thus beginning once more the never ending or continuous process of planning the extension programme.
The procedure followed for planning extension programmes, including agricultural development programme, is as follows:
A state government indicates to the districts & blocks the tentative outlays proposed in their respective areas under the various heads & the financial & other assistance that may be expected. The blocks prepare their respective annual plans, taking into account the special local problems & the local contributions & the state finances available. These are then consolidated districtwise, on the basis of which the state plan is formulated. The plans are prepared by the panchayat samities for the blocks & the zila parishads for the districts where the panchayati raj is in force. Where this set-up has not yet been introduced, the plans are prepared by the block development committee & the district development committee for the block & the district respectively.
The outlay of the state plans are finally approved by the Planning Commission.