If the price of pencils went from $2 a box to $10 a box, the demand will go down.
According to the theory of supply and demand, the increase in the price of a product causes the demand for it to fall because it is no longer accessible to consumers. It goes from being a current product to a luxury product, due to the increase in its value. Therefore, only a segment of the population can afford the expense of acquiring them, causing the demand to decrease.