Pre-operational Stage :  This period of a child's cognitive development usually begins at the age of 2, and lasts until about the age of 6. Thus, it usually coincides with the preschool age. In the pre operational stage the child's judgements are based on how things appear, rather than on adult logic. For example, a child may not realise that certain actions can be reversed. And therefore, she thinks that the volume of milk decreases as it is poured out of a thin long glass into a shorter wider one. Or that the same objects placed further apart in a lines to form a longer line, are more in quantity. Haven't you, at one time or another, exploited this inability of the preschooler to conserve? I have done so, for instance, when my four-year-old nephew insists on having a full cold drink. I pour the drink out from the half-full tall glass into a small glass. This way he gets a full glass of the cold drink, which makes him happy.

E1) Give two more examples from your own experience, where a child's judgement is based on visual perception, rather than on logic.

It is at this stage-that an average child learns how to handle some numbers consistently and how to apply them to a variety of everyday situations. A two year-old learns to distinguish between 2 toy cars and 3 toy cars merely by looking at the group of cars, in just the same way as she learns to use her visual perception to distinguish between a car and a bus. However, she cannot make out the difference between a collection of 8 cars and one of 9 by just looking at them.

She will have to learn to count to compare these sets or larger ones. Children appreciate the concepts of 'more' and 'less' much before they can even count or conserve quantity. This is because preschoolers think in patterns, and therefore, rely a lot on their own perception. Children can recognise shapes much before they can reproduce them. They can 'read' pictures much earlier than they can read words. You must have observed young children recognising human and animal drawings with ease, and yet not being able to reproduce even a square or a triangle with the same ease. Similarly, a young child who can remember how to go from one place to another often finds it very difficult to describe the route verbally or pictorially. It is a child's ability to recognise patterns that enables her to 'read' words that she has often seen, without recognising even a single alphabet.

If you give preschoolers some objects to count, you will be surprised to learn that they can recognise, count and even add and subtract small numbers before they can conserve number. They work with a small number of objects perceptually, and deal with them without counting. This is why numbers up to 4 or 5 are also called perceptual numbers.

 But the usual preschooler does not understand the idea of relative size. She can only compare two objects at a time. For her, quantity can be either "More" or "less", not "more than this, but less than that", and also not "more, less and lesser". For her, size is also either big or small, there's no in-between. Because of this, she may also not be able to order objects according to, size and length, or ,sequence events.