After the earlier image faded, the artist could remove the canvas from the camera obscura and continue his work. Caravaggio converted his studio into a kind of darkroom by filtering light through a purpose-made hole in his ceiling, using a biconvex lens and a concave mirror to reflect the image he planned to paint directly onto the canvas.

The use of a camera obscura to sketch the subject was not a new technique among artists, having gained prominence thanks to Leonardo da Vinci’s writings.

The device works by projecting reverse images of outside objects onto the flat wall of a closed box through a lens in an aperture. By attaching a mirror to the apparatus, artists were able to trace the exact dimensions of the image onto a piece of paper.

Caravaggio spent months refining his technique, adjusting the light and the size of the models.

However, by turning his entire room into a camera obscura, Caravaggio found himself working in the dark.

The experts believe this led him to create his own version of the faintly luminous, lead-based paint.

But the technique could sometimes give rise to distortion, said Grundy. ”In ‘Boy with a Basket of Fruit’, photographic discrepancies emerge with the lengthening of the subject’s head and neck as a result of the projection,” she explained. The size of the area being projected in the paintings depended on the size of the room, and Caravaggio was able to paint his subjects from ”far away” by altering the mirror and lens arrangement.

The many techniques pioneered by Caravaggio (1573-1610) have confirmed his reputation as one of the most revolutionary artist of his time, although he is probably best known for his mastery of chiaroscuro lighting.

I find the intrinsic v extrinsic argument one that has simmered for a very long time in the teaching profession. Were I work, we would never countenance house teams and points which were heavily extrinsic in their thinking – given and taken away as the occasion demanded. Along with that there was an old school type of thinking that went with school houses, lists or tables that showed which house was winning – and also laboured on which was loosing. Only finding a model which avoids publicly demonstrating who has lost would be considered.

We always looked for intrinsic means of motivating. The trouble is that all too often, children only recognise that they have done well if they see something in their hands as proof of their success. General praise and public applause would not be enough. Hence a drift into certificates, or more recently “Spotted”s.

“Spotted”s are little slips of paper which say on one side,

“You’ve been Spotted by….”

and the teacher’s name follows. Amazingly simple in it’s concept. But this is a ticket to a greater prize! These are given to children, not just for good work, but also for good behaviour. They child might not even have been looking to receive this small token of praise, but the hope is that (and is generally the case) that when good/kind behaviour, or concentration on a task, is rewarded, then the child feels a warm sense of achievement and will remember that behaviour in the future and repeat it.

The reward can be given for anything you wish and for any circumstance e.g. a good idea, reasoning and explanation, writing, reading, leaving another fidgety child alone, keeping their temper when provoked etc…

It’s aim is to promote a positive ethos and attitude – and unlike house points, can’t be taken away once given.

The child writes their name on the back and it goes into the ‘spotted’ box. Each class has the chance of having one name drawn out each week and (here’s the carrot) that child – as well as being seen to have done something positive by the whole school, also has the opportunity to choose something from the head teacher’s treasure box!

It has proved to be very popular. It does reward in an extrinsic kind of way for more intrinsic actions.