one embodiment of the invention consists of a set of blocks , say 12 blocks , each being rectangular in shape and adapted to be positioned edge - to - edge with other blocks on either side ( referred to as left - hand and right - hand edge ) in the manner of a row , and top edge and bottom edge in the manner of a column . each block incorporates a display screen over most of its front or upper surface , which forms part of an electronic visual display unit capable of displaying visual display material according to display data derived from a database . in this embodiment , the visual display material consists of a lower case letter of the alphabet which is displayed on the screen when the block is first activated . each block may incorporate a switch that allows it to be activated to deactivated , and operation of the switch initiates a start - up condition in which a pre - programmed letter is displayed . programming of the blocks may be such that different combinations in a row can spell out fifteen to twenty different words appropriate for teaching a young child to read . each block incorporates a means of displaying its orientation as far as top and bottom is concerned , which may invoke the shape of the block or an indicator displayed in the display screen . each block further incorporates a proximity sensor or sensor adapted to allow it so sense the proximity of another block aligned edge - to - edge with it , preferably involving contact between said adjacent edges , either at the left hand edge or right - hand edge or top edge or bottom edge . the proximity sensor , or other id sensor means independent of it , is adapted to sense the identity of each adjacent block . each block further incorporates a wireless communications unit through which it can communicate with another block to transmit information relating to its own identity and visual display material and the identity and location of adjacent blocks and to receive information causing the visual display unit to change the visual display unit material . each block preferably further incorporates an audio generator which is adapted to produce an audio response in accordance with internal programming information received via the wireless communications unit . it will be appreciated that a block with the communications , visual display and audio generator capability described above can be readily implemented using mobile telephone technology . proximity sensors , id sensors and touch and movement sensors can also be readily implemented using known technology . it will be appreciated that each block has its own power supply and incorporates a processor or processors which provide the required functionality . a set of blocks is adapted to be sufficient in itself to provide the functionality described below with the processors operating in accordance with pre - programmed instructions and the inputs from the sensors of each so as to produce visual and audio responses in the blocks . the constitution of an example one of the blocks is shown in fig1 , 2 and 5 . the internal construction of a block is shown conceptually in fig2 and in block diagram form in fig5 . fig3 illustrates how blocks of this kind can be placed in registration with one another both vertically and horizontally . fig5 illustrates the main components of a block . it will , of course , be apparent to the skilled person that this is a high level diagram illustrating only key components of the block . as shown in fig5 , a block 500 comprises a processor 510 , a memory 512 , an rf transceiver 514 , a screen 516 , a speaker 518 , a magnetic switch 520 , a touch sensor 522 , a movement sensor 524 , a docking port 526 and a battery 528 . the rf transceiver 514 enables the block 500 to communicate wirelessly with other , at least similar , blocks in the vicinity . the screen 516 and the speaker 518 allow visual and audio information to be presented to a user of the block 500 . the magnetic switch 520 is activated by the proximity of another , at least similar , block . the touch sensor 522 is provided at the exterior of the block 500 to detect a user touching at least that area of the block 500 . the movement switch 524 detects movement of the block 500 by a user . the docking port 526 is for receiving a memory card to load software / data into the block 500 . the block 500 also includes a battery 528 that provides power to allow the various devices within the block to operate . the processor 510 processes , with the aid memory 512 , information received from the rf transceiver 514 , the switch 520 , the touch sensor 522 , the movement sensor 524 and the docking port 526 to cause , as appropriate , the rf transceiver 514 to communicate with other blocks and / or cause the screen 516 and / or the speaker 518 to present information to a user of the block 500 . fig6 shows a tray 600 for use with blocks , e . g . 610 to 616 of the kind described above with respect to fig1 , 2 and 5 . the board 600 comprises a detector 618 for determining the location and identity of blocks placed on the board . the board 600 also includes a charger for recharging the batteries of blocks that are placed on the board . the board also includes a screen 622 and is configured to present information to a user via the screen in response to interactions of the user with blocks on the board . examples of how the set of blocks can be used as alphabet blocks will now be now described . sam is four and a half . she &# 39 ; s just started in her reception year at school where she &# 39 ; s learning to read and write . her parents are keen to help her learn at home and buy her a set of blocks with some preloaded reading software appropriate for her age . sam opens the box and takes out the blocks . her parents are standing over , curious about how they work . she goes to pick one up and the unit sounds the letter it is displaying . for example , ‘/ c /’. moving each of the blocks she realises they all do the same . in an alternative option , if there &# 39 ; s 15 seconds inactivity , one block could say ‘ try spelling a word , how about cat ’. alternatively pressing on a block could say , ‘ c sounds like / c /. / c / is for cat . move the blocks together to spell cat ?’ sam puts two of the blocks next to each other . starting with the one on the left , the blocks read in turn the letters they are displaying . for example ‘/ d /, / o /’. they then read the combined sound . for this example the blocks would say ‘ do ’. when she puts three ‘ random ’ letters together (‘/ c /, / f /, / g /’), they make no sound . she plays around with some different combinations until a word is spelt . for example , ‘/ c /, / a /, / t /. you &# 39 ; ve spelt cat . well done .’ at this point a cat leaps onto the screen , runs around and miaows . in an alternative option , the blocks prompt the child what to do next ? for example , ‘ now you can copy the word you &# 39 ; ve made onto its own block , by placing one below . or you can try and spell another word .’ when sam puts another block below the word she has spelt , the word jumps down onto that single block . it &# 39 ; s says ‘ cat ’ when she presses it . the three blocks that originally spelt the word are now free to be used for another word . as described above , each block is individually responsive to touch or movement and reacts audibly and visually depending upon what it displays . if each block is responsive to both truck and movement separately , then each can have a secondary response , such as giving an example of use . if a letter is displayed , e . g . “ c ”, the block sounds the letter as in it is said in the alphabet and phonetically . for example , ‘ c . c sounds like / c / for cat ’. an animation may play on the screen relating to the letter and the example given . a secondary response might suggest what the user can do next ? for example , ‘ can you spell cat ?’ if a word is displayed e . g . “ cat ”, the block sounds the phonetic letters for the word . for example , ‘/ c /, / a /, / t / spells cat ’. an animation relating to the word plays on the screen . a secondary response might suggest the spelling of another word from the available letters if this is possible . if a phonetic sound is displayed e . g . “ ch ”, the block sounds the combined phonetic sound ‘/ ch / as in lunch ’. the screen displays an animation of some food being eaten . when blocks are placed next to each other they react depending what is on each . this could be a phonetic sound e . g . ‘/ ch /’, a word e . g . ‘ cat ’ or random letters e . g . ‘/ k /, / r /, / f /’. if the user places individual blocks alongside each other then they respond according to the combination of letters they display . if a phonetic sound is created “ ch ”, the blocks sound the combined sound , ‘/ ch /’. they could also give a short example of use ‘/ ch / as in lunch , yum , yum , yum ’. if a word is created “ cat ”, the blocks sound the individual letters followed by the word . for example , ‘/ c /, / a /, / t /, spells cat . well done , you &# 39 ; ve spelt cat ’. the displays play a short animation . in this example a picture of a cat running between the two blocks . this happens whenever one of the joined blocks are pressed . if a new word is created ( plural or completely new ) by adding a letter or letters to a current word of phonetic sound , the response might be , for example , ‘/ c /, / a /, / r /, / t /, spells cart . are you coming for a ride ?’ or ‘ c /, / a /, / t /, / s / spells cats . here they come !’. the displays animate according to the word spelt if the word has an associated animation in database . so in the above examples , a horse and cart could drive on and off the screens , or several cats could start playing around . if a random set of letters are placed next to each other . for example ‘/ d /, / f /, / r /, / g /’, no sound is generated and no animation is displayed . animation and sound will only be available for some of the words that can be created using the blocks , as stated in a related response database held in one or each block or a central control unit . if a user places one block adjacent the top edge of another , the lower block inherits the property of the upper block . placing multiple blocks above or below will also cause a reaction between the blocks . for example , if the user places one block above another , and the top block shows ‘/ b /’ and the lower block shows ‘/ b /’, the lower block will also become a ‘/ b /’. a user can place a word spelt out over several blocks onto one block by placing a block below . this could also be used to join a ‘/ c /’ and an ‘/ h /’ on a single ‘/ ch /’ block . if a user has spelt a word or phonetic sound using three individual blocks , for example , ‘/ c /’, ‘/ a /’ and ‘/ t /’ spelling ‘ cat ’, the user can then place a fourth block anywhere under the three letter blocks and the word “ cat ” moves onto a single block . however , if a user tries to copy two random letters onto a single block it will not work . for example ‘/ g /’ and ‘/ f /’ cannot be joined on a single ‘/ gf /’ block . likewise if the user has two word blocks that don &# 39 ; t make a third word , they cannot be copied onto a single block . for example ‘ cat ’ and ‘ sat ’ cannot be joined to make a ‘ catsat ’ block . if a user has the word cat on a single block and wants to split it into three separate letters , they need to place three blocks below the word block . the three letters each go into their own block in right to left order below . an example of use of a set of alphabet blocks operating according to the above principles is illustrated in fig4 , in a number of steps 1 - 6 . 1 . blocks are taken out of the box and arranged on the floor . 2 . user puts ‘/ c /’ and ‘/ h /’ together , the blocks sound ‘/ ch /’. they put ‘/ g /’ underneath and copy ‘/ ch /’ onto it . trying to copy ‘/ t /’, ‘/ m /’ onto ‘/ g /’ doesn &# 39 ; t work . 3 . ‘/ a /’ and ‘/ t /’ are joined to make ‘ at ’ and copied onto a single block . 4 . ‘/ m /’ is put in front of ‘ at ’ to make ‘ mat ’. the individual ‘/ a /’ and ‘/ t /’ blocks are still joined to the top of ‘ at ’, but have no direct effect to the ‘/ m /’ as they are not directly above but to one side . ‘/ u /’ is put below the ‘/ m /’ of ‘ mat ’ and ‘ mat ’ is copied onto the single block , which is then removed ( not illustrated ). 5 . a ‘/ s /’ block is put in front of the ‘/ a /’ and ‘/ t /’ blocks to spell ‘ sat ’. as the ‘/ m /’ of ‘ mat ’ is now below the ‘/ s /’ block the word ‘ sat ’ is copied onto it . ‘ sat ’ is also copied onto the ‘ at ’ block . the two ‘ sat ’ blocks don &# 39 ; t interact with each other as a new word or sound hasn &# 39 ; t been created . likewise when a ‘ r ’ block is placed below either of the ‘ sat ’ blocks nothing is copied down . 6 . using the blocks here is a chain of various words that can be created following the principles described in the functional specifications . the invention is applicable to diverse areas , which include but are not limited to , play , entertainment , adornment and decoration , environment , industry and learning ( of , for example , languages , mathematics and musical skills / knowledge ). play applications may include a variety of playful games using the blocks and , optionally , a tray of the type mentioned in the introduction . these include new games as well as enhancements of typical existing board and card games with additional features ( by virtue of the fact the pieces ( blocks ) can change their image and emit sounds ) and the board ( interactive base ) can also change its image . further , new forms of toy such as farmyards and zoos can be created and become elements of animated stories . in relation to adornment and decoration , in the educational context , ia blocks can be worn as badges that can enable students to role play their various functions ( letters , sounds , numbers ) and interact with other badge - wearing children to form words , tunes and equations . beyond this , ia blocks have implicit emotive , aesthetic , interactive , and descriptive capabilities . blocks in combination can be used to trigger social and artistic interactions between people or create more complex installations . in environment and industrial settings variations of the devices can enable audio and visual data / systems alone or in combination ( e . g . for health and safety measurement and control ).