Using the correct type of surface to create art on is crucial! For example, if you try to paint on printer paper, you will quickly get a hole and it will be a complete mess! So, you should really get at least 2 types of paper for your kids, if not 3. You need one for dry mediums and one for wet mediums. The wet mediums are more important than the dry mediums, because if you don't have the right surface, it will cause a lot more problems, which in turn causes frustration, which is what we are trying to prevent.
The most ideal is if you get 1 for dry mediums (mixed-media paper), 1 for watercolors (watercolor paper) and 1 for acrylic paints (acrylic paint paper pad).
For acrylic paints, you need very thick paper, or canvas. Canvas is a type of fabric and it comes in 4 forms: rolls, pads, boards and stretched. For kids, we recommend pads. Rolls are for professionals who get them custom-stretched, stretched are hard for kids because there is no hard-surface to press down on, boards are ok - but we find that pads are the best option because they feel just like paper.