"Mr Osborne. May I be excused? My brain is full."

So says the caption of a Gary Larson cartoon. I am a huge Larson fan and have to admit, therefore, that my own sense of humour often tempts me towards the far side. Indeed I have used many of Larson's wonderful cartoons as lesson starters or thought provokers. Oh, and yes Gary, I have also purchased the collection of Gallerys, including the Prehistory of the Far Side, a personal favourite. I believe the compensation for sharing such treasures is the new generation of Far Siders as a result of these educational pursuits.

However, I believe the days have long passed since teachers saw their students as empty vessels needing to be filled, however small their brains may be. We have realised for some time that every learner is a composite of knowledge and experiences which have summed to produce a view of the world and everything which happens within it.

Unfortunately youth has more in common with maturity than we often care to acknowledge. Just as our partners or colleagues sometimes find it hard to get us to see another point of view, so students can be very dogmatic in the views they hold. Worse than that, when we back them into a corner, most people vigorously defend their views no matter how silly or futile the argument. Even the noblest of us have a certain pride about not appearing to be in the wrong, holding a viewpoint without adequate reason, or standing firm in the face of mounting evidence for a contrary view.

Our students are no different. They will not relinquish a viewpoint simply because you put forward a counterpoint. In fact some students play the 'in school, out of school' game.

"Well I know Mr Osborne will give me a mark if I say objects fall at the same speed, but really I know heavier objects fall faster."

This is a major misconception, though it is reinforced every time you drop something. The Physics of real life never quite seems to match the physics of the classroom. This is partly because the physics of the classroom requires brains of the calibre of Einstein to fully grasp all the implications and partly because the Van der Graaf generator is so touchy when the weather is not quite right.

What is important is to make sure teachers are constantly seeking ways of determining what students already know and how they can challenge these preconceptions.Cartoon and technology-based animations provide an excellent stimulus here because it is much easier to admit a mistake if it is actually made by someone else. If Mary, Kate and Ashley have a view about something and I think Kate is correct, then if later events demonstrates Kate's view was wrong, it can be easier to 'blame Kate' because it is less personal. "She was wrong".

This assumes you are able to present information with contrary views and you provide opportunities for your students to explore their own views and the reasons why they hold these views. It also gives us the opportunity to direct our teaching to the specific beliefs that are held in our classrooms. This is the real advantage of technology. Teachers can be so time poor that we need to use every resource we prepare, otherwise why bother? Technology for science education has given us the opportunity to massively expand our resource banks so we can draw specific examples out for specific situations. This is real assessment for learning as the way we teach is tied directly to the feedback we receive from our students.

Preconceptions always exist. We can either try to push contrary views over the top of them, or we can show our students that knowledge develops over time. A consistent approach, blended with appropriate technology for science lessons helps to fill the detail into the general picture we have of the world. The more information we gather, the more complete our view of the world becomes.