If you don't have kids, you've probably never heard of the fidget spinner. But for those who do, you've probably been dragged around a mall looking for this latest must-have gadget.

A small colourful, propeller shaped device, the fidget spinner has three weighted prongs made from plastic and metal which centre around a ball bearing pad.

The joy of the fidget spinner is how fast the prongs can be spun between the finger smoothly and effortlessly while it releases a satisfying whirring sound.

If there is one positive thing about these new toys, it's that they are actually a beautiful example of science and engineering in action.

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Underneath the central pad of a spinner is a bearing which consist of large and small flat sided circular rings.

Sandwiched between the rings are several ball bearings which lie within a groove at regularly spaced intervals. The ball bearings disperse the load and reduce friction which allows the spinner to rotate freely and smoothly. Originally the same bearing system was used for the wheels of skateboards and rollerblades.

The secret to the fidget spinner is in the additional weights on the ends of the prongs which add kinetic force on to the bearing, helping the spinner to spin for longer periods of time.

Although they have been marketed by some as helpful for people with anxiety, autism or attention-deficit hyperactivity disorder (ADHD) the scientific evidence supporting fidget spinners is scarce.

The few studies that have looked at how fidgeting could potentially help improve children's attention span have been focused on young people diagnosed with ADHD.

In those studies, the students with ADHD did show some improvements in their accuracy when assessed on computer-based tasks when they fidgeted compared to when they didn't.

However, these studies looked at natural fidgeting by measuring movements such as foot tapping rather than using a handheld fidget device.

The study also showed that similar-aged children who had not been diagnosed with ADHD did not perform any differently when fidgeting compared to when they were sitting still, meaning the fidget spinner is unlikely to provide any attention-span benefits to most children.

Spinning a plastic toy is very different to tapping your feet, so it should be noted that any marketing pitch using a correlation between improved attention span and fidget spinners are not backed up by solid scientific evidence.

Science aside, the bigger controversy surrounding fidget spinners today is around how to cope with so many in schools.

What is a quiet whirring sound for one spinning device can transform into a cacophonous classroom chorus when many are spun at once and schools are starting to ban the toys.

When the constant whirring is added to the intermittent noise of spinners being dropped and ball-bearings rolling across the floor by students practising their spinning tricks under the table, fidget spinners are fast becoming classroom learning distraction creators.

Banning fidget spinners in classrooms won't stop the craze and the digital world has already come up with virtual solutions by creating fidget spinner apps which provide non-tactile but silent versions of the toy.

As with hula hoops and Rubik's cubes, fad toys really take off when a sense of competition is added. With thousands of new fidget spinner videos online, showcasing stylish ways to throw and catch the spinning devices it looks like the online skills challenge has already started.

For those of us who are still old school and not spinning devices under the table, don't fret - the original solutions for diverting bored energy such as doodling or pen-clicking are still freely available to us all.