Extra sensory perception;Hands on
Every now and then a technology appears that sends a shockwave through its field. In the case of sensors for science teaching, such events are rare as, unlike the frantic pace of computer development, sensor technology has advanced at a modest rate. Until now.
The jolt comes from a data-logging system with remarkable build quality, ergonomics and performance. What this means in practice is a system that makes science more accessible by taking readings from experiments at incredible speed.
Meet the California-developed Pasco system, based around a Science Workshop 500 Interface, which accepts a bewildering array of 40 sensors. For example, plug in a sound sensor and, using the Data Studio software (see opposite), you can bring an oscilloscope display on the screen. Play a note and a soundwave appears; play two and you can watch how their waves interfere; try a "fast Fourier transform" and their sound frequencies are computed live before your eyes.
Normal school data-loggers that take 10, even 100 readings a second, will not do this. They will let you monitor a beaker of cooling water or the photosynthesis of a plant in the sun. But they would need to rev up from a crawl to lightspeed to match the Pasco system's 20,000 readings a second. And at this rate, data-logging gets exciting. For instance, if you record a soundwave with two sound sensors placed apart, you can see the wave reach one before the other. You can then measure the delay and work out the speed of sound. If you use a light sensor, you can examine how the flicker from two fluorescent tubes interact. Use a voltage sensor, and you can note the pulse of electricity a magnet generates as it drops through a coil.
There are also sensors that measure force, distance and acceleration, enabling new experiments to demonstrate Newton's Laws. For example, if you attach a trolley to a spring, these sensors actually measure how a push accelerates it. What was previously invisible is now easily measured; science has never been so "in your face".
The distance sensor is more familiar - it measures by sending out soundwaves and seeing how quickly they bounce back. Younger pupils can learn about distance-time graphs as they see how a Pasco distance sensor responds to their movement. And while older students enjoy experiments on forces by attaching a sensor to a runway to examine a trolley's speed, teachers will appreciate how neatly the device clips on, how its shape protects it from knocks. Meanwhile, the circuitry inside allows accurate measurements to within 15cm - other sensors become confused at short range - making them suitable for advanced level work.
While physics teachers have the most fun, chemists will find not only electrodes to measure pH but a host of others to measure nitrates, sodium and potassium. And while it's good to know these exist, they will find the colorimeter indispensable for measuring reaction rates. Rarely seen in the UK, this must-have item shows how fast solutions change colour without interference from stray light. Given the Pasco treatment, the "smart" colorimeter automatically adjusts readings and selects the best light filter for the reaction. As you would expect these days, it has built-in software to do the job.
There is much to commend. A gaze at a Pasco catalogue takes the breath away for the myriad of accessories on offer. Best here is the track and trolley kit, which is seemingly the core of every imaginable dynamics experiment, likewise for an optics kit. But also impressive is the way every piece of equipment seems to work together: you can put away the Blu-tak thanks to the sensors' brackets that neatly fix them to trolleys. Seemingly minor features like flexible cables, compact sensors and easy storage echoes an obsessive, American attention to quality. The prices for Pasco equipment might appear rather high at first glance but they actually represent extremely good value for money.
The Pasco system is so outstanding it might have been developed in a parallel universe. It offers a fresh look at how techno-logy enhances science teaching and will surely send some old ideas into hyperspace.
Pasco UK (Instruments Direct)
Tel: 0181 560 5678
Science Workshop 500 pound;410; Science Workshop 750 pound;750; A starter demonstration kit might include: Introductory physics bundle pound;1,000; Extra temperature sensor pound;50; Introductory Dynamics System pound;290; Data Studio software for MacPC
A starter set for students would include the 500 interface, two temperature sensors and, if possible, one distance sensor.