What do you meant by "matter is not continuous"
The term continuous means something which does not have any breaks and is present in single, unbroken form. In reference to matter, continuous means something which does not exist in discrete (separate) form. Particle form is just the opposite of continuous, means something which is present in the form of distinct particles. Now the block of wood is not present in the form of small distinct particles, but in a single unbroken form. Hence it is continuous. On the other hand, sand consists of very small, discrete particles which can be seen very distinctly. Thus, sand is an example of particle form of matter.
However, matter is not continuous but particulate in nature. It is composed of very small particles called atoms.