You can change the shape of solids. You change the shape of sheets of lumber by sawing it in half or burning it. Liquids Milk is a liquid. Milk is liquid matter. It has a size or volume.
Volume means it takes up space.
But milk doesn't have a definite shape. It takes the shape of its container. Liquids can flow, be poured, and spilled. You can't spill a wooden block. You can drop it and it still has the same shape.