A recent article on mathematics teaching was headed "We have seen the future and its screen is small". I am not sure that the graphical calculator is the future, but its impact has spread from A-level work to lower secondary pupils and even into some primary schools.
A limiting factor until now has been the relatively high price. Given that the screen of a graphical calculator is often difficult to view from an angle, it is important for each student to have her or his own machine. This is now increasingly possible as prices drop and manufacturers bring out machines with fewer functions.
The TI80 and EL9200 are good examples of this trend. The former clearly belongs to the same family as the TI82 and TI85, with a similar layout of good, positive action keys, and the cursor buttons in a contrasting blue. Its screen area is smaller than the other two machines, measuring approximately 3. 5cm by 3cm, and is flat, not inclined as in the more expensive models.
This means that the angle of viewing is sometimes more critical, but it is possible, nevertheless, to get reasonable results for the types of graph likely to be encountered at GCSE level and below, and the manual, with its wealth of worked examples and clear layout, is exemplary.
The TI92 demonstrates the convergence between calculators and palmtop computers. It is about the size of a video cassette, with most of the keyboard parallel to the longest edge. This part of the keyboard comprises a QWERTY and numeric layout, similar to that of a computer.
There is virtually no limit to the type of graph you can produce, including 3-D plots which can be rotated. The geometry application allows you to plot pre-defined shapes or to define your own, and then to manipulate them, measure them or analyse them.
The TI92 is a well-designed and engineered machine and I can see it rapidly becoming a deeply desirable possession for advanced students and their teachers.
Two OHP calculators from Casio are large enough to provide good displays on the projector. All their keys are mounted in transparent plastic, thus allowing the class to follow all the operations. The OH-450L is a simple calculator, while the OH-82 is a 10-digit scientific calculator. Both would be useful to teachers who need to explain calculator techniques to their students.
* Texas Instruments TI92
Graphical calculator, Pounds 149.99 (+VAT)
Texas Instruments TI80
Graphical calculator, Pounds 36.73 (+VAT) Texas Instruments, Kempton Point, 68 Staines Road West, Sunbury-on-Thames, MiddlesexTW16 7AX. Tel: 01784 212739 * Casio OH-450L OHP display unit
Pounds 15.75 + VAT
Casio OH-82 Super OHP display unit
Pounds 18.50 + VATCasio Electronics, Unit 6,1000 North Circular Road, London NW2 7JD. Tel: 0181 450 9131. Stand IT64