AV aids include non-projected aids like pictures, posters, and bulletin boards as well as projected aids like film projectors and overhead projectors. They make learning more interesting and effective by providing sensory experiences that remove barriers to communication and help students develop concepts. Non-projected aids do not require electricity, are abundant and easy to obtain, and can be used at various instructional levels. Projected aids engage students through enlarged images and movement, stimulate learning, and allow topics to be adapted to different audiences. Both types of aids have advantages in teaching if used properly.

1. AUDIO-VISUAL AIDS (AV AIDS)
AV aids are devicesorproceduresthathelp tomake : learningmore interesting &effective.They
are source of sensoryexperience whichmakeslearningpossible &easy.
ADVANTAGE
 Theycreate an atmosphere of goodfeelings&mutual liking .
 Theyremove barriersof commoncommunicationinthe classroom.
 Theyprovidessensoryexperience whichmakes thingsclear.
PURPOSES
 AV aids supply a concrete basisforconceptual thinking&hence reduce meaningless wordresponses
of students.
 AV aidsare usedto create interestinstudents.
 Theyare usedto make Learningpermanent.
 Theyoffera realityof experiencewhichstimulatesself- activity.
 Theyare usedto developcontinuity of thought,thisisespecially true of motionpictures.
 Theydevelopthe growth of meaning& vocabulary.
 Theyprovide experience noteasilyobtainedthroughothermaterials&contribute tothe efficiency,
depth& varietyof learning.
TYPES
AV aids maybe dividedinto 2
1. Non-projectedaids
2. Projectedaids
NON- PROJECTED AIDS
It has beenfoundby studiesthatabout75% of knowledgeisreceivedthrough the eyes.Thisfactthrows
clearlightsonthe significanceof visual aids inteaching- learningprocess.Some of the mostcommunity
usedvisual aidsare;
# Picture # Posters # Bulletin board # Chart # Graph
Non-projectedaidsare those aidswhichare used withoutanyprojection.Sothey translate abstract
ideasintoa more realisticformat.Theyallow institutiontomore formverbal representationto a more
concrete level.
ADVANTAGE
 Abundant& easilyobtained.
 Requiresno electricity.
 Appropriate forlowbudget.
 Notmuch artisticabilityisrequiredin the use of these visual aids.
 Can be usedinmany waysat all levelsof instruction&discipline.

2.  Usedto stimulate creative expressionsuchastell stories orwritingstories.
 Many of themcan be convertedintoprojectedaids.
 Some of them can be projectedthroughanopaque projector.
PICTURES
Picturescan be used as a teachingaids& theyare quite useful indemonstrationlesson.
Teachermade charts & picturesare to be preferredtocommercially produceones.
ADVANTAGES
o Everythingachildlearncan be presentedgraphically withthe aidof pictures&brightly coloured
diagramswhichwill excitehisinterest.
o Theycan be usedtoteach language,geography,history,science oralmostall the subjects of the
curriculum.
Some considerationwhile usingpicturesas teachingaid ;
o Picturesshouldbe bold,direct&sufficientlylarge.
o Picturesshouldnotbe overloaded withinformationratherthey shouldsticktothe maximum .
‘One picture,one idea'.
o They must be neatly drawn& properlydisplayedsothatattentionof the studentsiseasily
drawn,to the pointsto be taught.
POSTERS
It is a visual combinationof bolddesign, colour&message whichisintendedtocatch hold
of attentionof passerata galance.Postersare the graphicaidswithshortquick & typical messageswith
attentioncapturingpaintings.
PURPOSES
 To provide general motivation.
 To create an esthetic/atmosphericeffect.
 To communicate amore general idea.
 To thrust the message forleadingtoactionforthe classroom& community.
PREPARATION & RULES
• To do a special job. • To promote one point.
• To supportlocal demonstration. • Tell the message atsingle glance.
• Use boldletters. • Use pleasingcolours.
• Plannedforspecifiedpeople. • It shouldplace , where peoplepass.

3. FEATURES
o Brevity - Message shouldbe concise.
o Simplicity - Message shouldbe easily understandable.
o Idea - Shouldbase onsingle idea &itshouldbe relevant.
o Colour - Suitable colour&combinationshould be usedtomake the posterattractive &
eye catching.
o Display - White displayingone shouldbe sure tofinda place where there isadequate
light& where the large populationwill seeit.
o Limitedtext - Every posterreliestosome extentonwrittenwordstoconvey aspecificidea
or message.Fewwordsshouldbe used.
o Title & captions- It shouldbe brief, clear&writteninneatmanner.A five wordcaptionis the
best.Do notbreak the caption.Never write the captionvertically,as itisdifficulttoread.
o Postershouldbe simple,dynamic,withaclearcut message.If wordsare used,theyshouldbe
clearly written&easyto read.
o It shouldconvey onlyone message.
o It shouldencourage action.
ADVANTAGES
 It isuseful forplaying informationonapermanentortemporary basis.
 It can be preparedcheeplyif onlyone or twocopiesare needed.
 Presentationof posters isnotmessy&itsavestime also.
 It isportable.
 It attracts attention.
 It conveysthe message veryquickly.
 It doesn’trequire adetailedstudy.
 Good posterslead toactionwithgood motivation.
 It can stand alone &is self explanatory.
DISADVANTAGES
 It doesn’talwaysgive enoughinformation.
 Whena posteris seenforlongertime,itmaynotattractive. So itshouldbe dynamic.
 These couldpresentproblemsintransportation &storage dependingonthe number&bulk.
 These have limited dramaticeffectof presentation.
 These shouldbe bigenoughtobe useful effectively.
BULLETIN BOARD
It is a displayboardonwhichlearningmaterial onsome scientifictopicisdisplayed.Itisone
of the effective aidsof teaching&sothere should be a bulletinboardnearthe science room.Itis
generallyof the size of ablack board,butsome timesevenbigger dependingonthe wall space available.

4. It usedfordisplayingbestworkof students.
Eg; Interestingscience news,brochure,cartoons,poems,sketches,pictures, thoughts,
announcement,publications,posters,newspapercutouts.
It isa softboardwhichwill holdpinsortags almostsuitable. Simpledevicesplacedeitherindooror
outdoor.
An effortbe made tochange the material on bulletinboardasfrequentlyasinpracticable.
Wheneverteacherstarts anewtopic he may askthe students todisplaythe concernedmaterial onthe
bulletinboard&teachershouldspecificallymentiontothe studentthe displaymaterialonbulletinboard
while teachingatopicto the class.
It shouldbe made a projectfor the pupils&the material for displayshouldbe the resultof active
participationof pupils &the teacher.Maximumeducationalvalue isderivedif the pupilsare made in
charge of it& the teacheracts as a guide.The pupil take beeninterestindisplayingsome attractive
material &thus theircreative abilityis developed.Some change isnecessaryeverydaytomake roomfor
contributions.The studentsshouldbe encouragedtogive regularcontributioninordertokeepthe
bulletinboarddynamic.
ADVANTAGES
 Explains importantevents,reports,special activities.
 Provides opportunityfordevelopingcreativeness,responsibility &otherabilitiesinthe pupils.
 Good supplementtoclassroomteaching.
 Helpsinarisingthe interest of studentsinaspecificsubject.
 It can be effectivelyusedasafollow up of chalkboard.
 Such boardsadd colour& liveliness &thusalsohave decorative value inadditionto their
educational value.
 Such boardscan be convenientlyusedforintroducinga topic& forits review aswell.
DISADVANTAGES
 Noteffective forilleterate group.
 Takeslot of preplanning&preparation.
 Theycan’t be used for all inclusive teaching.
 Theycan be usedonlyassupplementaryaidstosome otherteachingaid.
 At times,itbecome verydifficulttomake properselectionof displaymaterial forcertaintopic.
PROJECTED AIDS
A projectedaidisone inwhichitemtobe observedare projectedonascreenusing
mechanical devices.These aidsare foundtobe veryeffective becausemovementcanbe addedto
sound& hence a realisticexperience canbe provided.
Projected visual aidsare detainedasmediadesigninwhichstill imagesare enlarged&
displayedonascreen.The typesof projectedvisuals,thatwe can use inclassroomare: software,digital
visuals&documentcameras.

5. Projectedaidsare picturesshownuponascreenby use of a certaintype of machines.
Eg; • Film&filmprojector • Filmstraps & filmstep projector • Slides&slideprojector
• Epidiascope & episcope • OHP • TV • LCD • Computer • Mobile • Tablets.
ADVANTAGES/ VALUES
 Provides greater enjoyment in learning.
 Stimulate more rapid learning.
 Increase retention: larger percentage& longer retention.
 Makes teaching situation adaptable to wider range.
 Compulse attention.
 Enlarges or reduce actual size of objects.
 Brings distant past & present into the classroom.
 Provides an easily reproduced record of an event.
 Influence & changes attitudes.
OHP ( OVER HEAD PROJECTOR )
The OHP is the most used in all audio- visual aids. This is called Over Head
Projector, because it projects the image behind & over the head of teacher.
It projects transparencies with brilliant screen images suitable for use in a lighted
room. The teacher can write or draw diagrams on the transparency while he teaches; these are
projected simultaneously on the screen by the OHP.
In OHP, a transparent visual is placed on a platform at the top of light source. They
passes through the transparency & then is reflected at an angle on to the screen, placed at the
back of teacher. The enlarged image will be much effective. More over as the slide can be got
ready earlier, time can be saved. The written matter will then get projected on the screen.
PRECAUTIONS DURINGPRESENTATION
 Keep the screen above the head of participants.
 Keep the screen in full view of participant.
 Make sure you are not blocking any ones views when presenting.

6.  Darken the room appropriately by blocking out sunshine & dimming near by.
 Turn the screen off b/w slides if you are going to talks for more the 2.
 Talk to the audience, not to the screen.
 The screen should be wide enough to make the projected material large enough to
be seen by the whole class.
 The seating arrangement of students should also be properly made so that they can
see& listen w/o difficulty.
PURPOSES
 To develop concepts & sequence in a subject matter area.
 To make marginal notes on the transparencies for the use of teacher that can carry
w/o exposing them to the class.
 To test students performance while other classmates observe.
 To show relationship by means of transparent overlays in contrasting colour.
 To give the illusion of motion in the transparency.
 Used in most lecture & seminar rooms.
ADVANTAGES
o It permits the teacher to stand in front of class while using projector, thus enabling
her to point out features appearing on the screen by pointing to the materials at the
projector itself & at the same time, to observe the students reaction to her
discussion.
o Gains attention of student.
o Additional information can be provided to the already prepared transparencies as &
when they are projected.
o Other materials can be superimposed on the prepared transparencies, as they are
projected & when there is a need for it, this can be done using colour pencil or fell-
tip pen.

7. DISADVANTAGES
o It can’t projects or enlarge slides on the screen, if electricity is not available at the
time of presentation.
LCD ( LIQUID CRYSTAL DISPLAY )
LCD panel is designed to project on screen information of a microcomputer onto a
larger screen with the aid of a standard OHP projector, so that large audience may view on
screen information w/o having to crowd around TV monitor.
LCD projector is the most advanced & sophisticated projecting aid. It is used to
present a topic in the classroom or infront of a large audience. We can demonstrate the real
world situation & its stimulation in the classroom in a theatre like atmosphere. In the area of
educational technology we can replace all other projected & non projected aid with only a
single LCD projector & a computer system. We can present a topic by using computer made
slides, graphics, pictures, video clips, movies & special effects. We can bring the real world
situation into a classroom by way of movies & multimedia effects.
ADVANTAGES
• Easy disposal. • It has no geometric distortion.
• It is much thinner than a CRT monitor. • Used in battery powered electronics.
• Light weight & compact. • Excellent contrast.
• Doesn’t rely on phosphores. • Low flicker rate.
• It is very compact , thin& light CRT displays. • Uses a smaller pixelated format.
• Screens are availablein vast range of size.. • It doesn’t affect by the magnetic fields.
• Superior resolution. • Life span: 50,000 – 100,000 hours.
• Energy efficient, low power. •Shap resolution & images.
• It can be made in large size of over 60o
inchor 150 cm diagonal
• Due to lowpowerconsumption,smallheatemittedduring operation.

8. • Producesverybrightimagesdue tohighpeakdensity.Verysuitable forenvironmentsthatare brightly
lit.
DISADVANTAGES
 In hightemperature environments,there islossof contrast.
 It isrelativelybright butnotsuitable forverybrightlyenvironments.
 It consumed alot of electricitywhichproduce alotof heat.
 It has individual liquidcrystal,whichcan’t complete all blockof the backlight.
 From the viewingangle,the colours&contrastnot consistent.
 The aspect ratio& resolutionare fixed.
 Slowresponse times &scanrate conversionresultinserve motionartifacts&image
degradationformovingorrapidlychanging image.
 The colour& contrastfrom variousviewinganglesisinconsistent.
 Motionblur iscommon.
 Featurespoorblackon dark imagery.
 Nevertechnologycostsmore.
 Fixedresolution.
 Pixel baseddisplaymaybe stuckonscreen.
 Withbrightnessfrombacklighting,imagerymayappearflat.
 Imagerynotas good withanaloginterface.
ANASWARAAJ
No: 4