Put a plastic office chair mat under your kids art table to protect your carpet!

• They come large enough (46" x 60") for most kids tables, or even use two
  
• Buy from Staples, Office Depot etc.
  

If you DO get paint on the carpet, try these removal techniques

• Don't scrub the stain, blot and wipe
  
• Avoid applying too much liquid, you don't want it to saturate the carpet padding which can get moldy
• Always test clean a patch first
• If you have pets, don't use ammonia based cleaners as it may trigger your pet to relieve himself on that spot
• Try 1 part water + 2 parts white vinegar, let is sit, then blot with clean white cloth
• Try a paste of cornstarch and water, let dry, then vacuum up. Repeat.
• OxiClean can work well but test a patch first in case of color fading