Yes, it's yet another Logo idea... LogoTile is a small add-on, or microworld, all about tessellations, published by NCET, available for BBC, PC, Nimbus and Archimedes computers and to be used within the version of Logo you have for that machine. Though available in its own right, it will also be included in the "Tiling" pack that NCET are publishing, which includes other resources on pattern making, such as the software Mosaic and Newtiles, and booklets and work cards.

It is a small microworld, simple, limited, easy to learn, easy to use and therefore of definite value. A pupil with an elementary knowledge of Logo (enough to understand the idea of making the turtle move by typing in instructions and the essential clear screen command) can easily produce a display of tessellating squares, triangles or hexagons in a lesson with little prompting from the teacher. A Year 11 pupil of mine said after 45 minutes "This is fun. Can I do more next lesson?"

All the new procedures the microworld offers are fully documented in the accompanying documentation, which also contains starters and hints (for teachers). The most important procedure is tile, which allows you to draw any size of regular polygon. Other polygons, or tiles, can then be added to the picture. For example, touchingtile (or tt for short) will allow you to add a polygon onto the side of the existing one.

Other procedures move or turn the turtle using units of angle and distance which are related to the tiles themselves, like so:

tile 8 draws a regular octagon, leaving the turtle at the centre facing upward.

tt 8 4 draws a square touching the octagon on the side the turtle is facing. The turtle returns to the centre of the octagon.

rturn 1 8 makes the turtle turn towards the next side to the right within the octagon

tt 8 8 draws an octagon touching that side.

Thus a semi-regular tessellation can be built up. I have used LogoTile with less able ("Green" in SMP terms) Year 10 pupils and in one lesson, without much prompting, some did produce a semi-regular tessellation of octagons and squares. Others concentrated simply on squares or triangles. Most found the microworld easy to find their way into, were able to produce something quickly and appreciated getting a good display to print out. The standard procedure fill fits neatly with LogoTile so that you can easily colour in tiles and produce interesting pictures. When asked what they'd learnt, one said "A lot", though another said bluntly "I learnt nothing". (This comment is worthy of longer discussion along the lines of how you get very weak pupils to recognise when they've learnt something rather abstract.) On what they liked best, comments included "Being able to jump", "Changing the size and shape", "You could do your own thing." One pupil thought it would be improved by using the mouse. (Using the mouse to move the turtle... are we going mad?)

It was interesting to observe how some pupils were reluctant to move the turtle at all and were happy to build up a picture centred around it, whereas others boldly stepped into the unknown with jumpforward. I felt that the microworld made tessellations easily reachable by such pupils. In a fairly natural way they were able to concentrate simply on the fitting together of the shapes without too much worry about angle and distance. Some may see this omission as a drawback, which perhaps it might be for more able pupils. A teacher commented to me that her top ability Year 9 group enjoyed using it after trying first to create their own tessellation procedures. Perhaps the microworld makes tessellations too "easy" for brighter pupils. It depends on what you are aiming for.

Logo, it seems to me, is one piece of software ideally suited to the less able. Many teachers have commented on how their classes, normally difficult to motivate (particularly when it comes to any writing), are keen to get on the computer and "do some Logo". However, the process of building procedures (in RM Logo at least, but not LogoWriter, for the PC, which gets round this problem and there is a version in the LogoTile pack for LogoWriter), whereby the screen changes from the graphic display to the editing display, and all existing graphics are wiped, is a distinct disadvantage. Pupils don't like to lose their work even if it is does mean that in the long run they might get on more efficiently. We rarely get the time now to take advantage of "building" anyway. LogoTile reduces the need for building procedures and yet can produce striking results fairly quickly. This, for the less able, would seem to be ideal.

There are some minor drawbacks: some pupils kept typing rt 1 8 instead of rturn 1 8. Couldn't the procedure have been called turnr (or just r)? Others got into a muddle at first over the ordering of the inputs, for example tt 4 5 instead of tt 5 4. Many of the primitives require two inputs, one being the size of the polygon that the turtle is currently within. Why was this thought necessary? If the turtle is at the centre of a hexagon, what first input other than 6 would you want to use for touchingtile or jumpforward? Perhaps you might want to jumpfoward from a position that is not tiled at all, but in that case why not have a procedure that tells Logo what size tile the turtle is within, whether drawn or not? This would imply a different approach to the microworld, whereby you would type tilesize 6, say, followed by tile, instead of tile 6. It isn't always the first input that indicates the current tile either, which is additionally confusing. The omission of this input might have avoided some muddles, but overall the pack is well worth the (very low) price.

For further details, contact NCET, Sir William Lyons Rd, University of Warwick Science Park, Coventry CV4 7EZ