This is the classic method that involves a bit of cooking on the stovetop - I prefer it because cooked playdough has a better texture than uncooked varieties. If you want the kids to be able to do it all themselves, try this uncooked playdough recipe.
Warning: Keep away from dogs and other pets. Playdough smells like people food but contains lots of salt, and a hungry dog can eat enough to cause a dangerous salt imbalance.
Step 1: Ingredients
Basic ingredient ratios:
2 cups flour
2 cups warm water
1 cup salt
2 Tablespoons vegetable oil
1 Tablespoon cream of tartar (optional for improved elasticity)
food coloring (liquid, powder, or unsweetened drink mix)
Step 2: Mix and heat
When the dough pulls away from the sides and clumps in the center, as shown below, remove the pan from heat and allow the dough to cool enough to handle.
IMPORTANT NOTE: if your playdough is still sticky, you simply need to cook it longer!
Keep stirring and cooking until the dough is dry and feels like playdough.
I've gotten many comments asking about sticky dough, so please just keep cooking a bit longer and it will work!