Momentary advantage

22nd November 1996 at 00:00
Time can be measured by all sorts of devices in all sorts of subjects, ranging from science to PE. Now, says Gerald Haigh, the hour of decision is at hand

Schools use timing devices for two separate, though overlapping, purposes. They can be tools to measure the passing of time in a whole range of scientific experiments, PE and games, and a number of classroom activities. Or they can be used as aids in teaching about time itself. By and large, the simple timers here are the ones which are more suitable for visually demonstrating the passing of time.


Sand Timers

We saw two sorts. The Ballotini sand timer comes in a set of three, timed for 30 seconds, one minute and five minutes. Each has different coloured sand. They are robust and accurate - the five-minute timer, on three tests with two different digital clocks, ran less than two seconds fast.

Mandy Rogers, the Warwickshire primary teacher who helped me look at this collection of timers, recalled a sequence in an Office for Standards in Education preparation training video (Let There Be Light Pounds 52.87 from Questions Publishing) in which the teacher uses a sand timer to encourage her children to tidy up quickly. "I'm going to do that in my class," Mandy said.

The other sand timer we saw, the Invicta plastic sand timer, comes with the sand separately packed, and can be opened so that you can fill it. Children can thus experiment with materials other than sand, and can try calibrating the timer themselves.

John Stringer, adviser and consultant with the Association for Science Education, who also looked at these products with us, pointed out that children can also devise ways of making their own sand timers using yogurt pots or similar containers. "But it's difficult to get really fine sand, and, surprisingly, the sand quickly erodes the plastic so that the home made timers become inaccurate. Cooking salt is better." Both of these sand timers come with workcards.

Water Timers

The water clock is one of the great classical artefacts. The Karnak Water Clock in the British Museum, with its complicated markings, is an astonishing sight. (The Egyptians always measured 12 hours of daylight. So their hours varied in length as the year progressed. The Karnak Clock takes account of this).

The basic idea behind water timers is simple enough - you fill a vessel with water, and it runs out through a hole. As the vessel empties it measures the passing of time, perhaps by uncovering calibrated marks. Again, children can obviously learn much from making their own versions of clocks like this. The Invicta water timer is basic - a small plastic container with a stopper underneath and lid on top - and comes in a set of three. You fill the container with water, remove the stopper and the water runs out for half a minute, one minute or two minutes. The flow is controlled by the size of a small hole in the lid which allows air in at a controlled rate.

This principle is interesting but John Stringer felt that by comparison with varying the size of the exit hole, "it adds to the difficulty of explaining the clock to young children".

Rocking Timers

These Invicta products are plastic semi-circular "rockers", about 15 cms high. You put one on the table, tip it over so that the triangular top touches the surface and let it go. It then rocks to and fro for a length of time which can be adjusted between five and 25 seconds.

"I guess we'll find these are not very accurate," said John Stringer, and he was right. Set for 25 seconds, for example, my timer would not run for more than 18.

Young children could use them to make comparisons but they are not accurate enough to measure periods of time. They also vary depending on the surface: they skid on a smooth wooden or plastic table top, and a carpet slows them down. A piece of paper helps - the timer will rock within the confines of an A4 sheet. Neither of my advisers was particularly enamoured of these, and both of them, independently, wondered about the strength of the thin plastic extended top.


Big timers

We had two. One was the traditional Smiths seconds timer - clockwork, with a face and two hands, measuring seconds and minutes up to an hour. There are three buttons - start, stop and re-set. For John Stringer, this was an old friend. "It's been improved though.

You used to be able to hit the reset button instead of the stop button by mistake, and lose your information. Now you can't press the reset button when the clock is running."

Mandy Rogers, who comes from a newer generation of teachers, was not so impressed. "I don't think children can read it easily, and sort out what the two hands are saying," she said.

Both she and John, though, did like the large LCD clock timer which is effectively the modern equivalent. "Large digital display, easy to see, " said Mandy. "It's easy to use, too" added John, "and it only counts in seconds which is good. Many digital watches count in hundredths of a second, which is confusing for children and there is no need for that level of accuracy in school."

A slider on this timer selects the function (ordinary clock, alarm, a timer which will count down as well as up) and there are two buttons on top, one for start and stop, one for reset and split time. "This is one I would get" said John, and Mandy, too, put it aside as a choice to buy.

Stop Watches

Stop watches go out on the field, down to the swimming baths, and may well be sidetracked into the science labs. Each of the ones we saw here was effective, though you would need to take full account of how they were to be used before spending money.

We saw three watches. The Cronus 600 Actionwatch is relatively cheap (only relatively - there are cheaper ones around). It works and does the job, but we all preferred the the ASTAccusplit stopwatch, which is water resistant and has a good robust feel. John liked it particularly because "you can use it easily with either hand - there are two identical stop and start buttons, one on each side." It is not cheap though.

If you do really want a multi-function stop watch for athletics or swimming coaching, the Spordas 500 sports chronometer is worth looking at. It fits the hand nicely, is brightly coloured so you can see it when you put it down, and it has a full range of functions for athletics and swimming coaching.

All of these watches have frantic hundredths-of-a-second displays - not helpful when children are using them. You can also get into a tizz with the buttons, so that you end up not knowing what the watch is showing (AST Accusplit and Spordas are best here). This, said John Stringer, "Happens all the time when I use digital stopwatches with teachers on in-service courses".

Finally, we saw a traditional, spring-driven stopwatch. It is made of metal and has a clear face. We loved it, but it is relatively expensive, and although it shows an analogue, rather than digital face, we could not easily think of obvious advantages for school use. "I wouldn't like it bouncing round my neck" observed Mandy, the voice of the Nineties. It is also susceptible to being dropped or overwound. It is easy to imagine that an MGB-owner would prefer it, and, with a bit of engraving, it would make a good gift for a PE teacher.


Ballotini Sand Timers The LCD Clock Timer

All of the equipment reviewed here was supplied to us by NES Arnold, Ludlow Hill Road, West Bridgford, Nottingham NG2 6HD. Tel: 0115 945 2200. The prices quoted are from their catalogue. The same, or equivalent products may be available elsewhere at different prices

Ballotini Sand Timers set of three Pounds 42.95. Invicta Plastic Sand Timer with separate sand Pounds 10.95. Invicta Rocking Timers set of three Pounds 13.95. Invicta Water Timers set of three Pounds 9.50.

Smiths seconds timer Pounds 36.95. LCD ClockTimer Pounds 37.95. Cronus 600 Actionwatch Pounds 7.25. ASTAccusplit Stopwatch Pounds 23.50. Spordas 500 Stopwatch Pounds 19.95. Mechanical stopwatch Pounds 29.50.

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