Use this recipe with children to make the best ever homemade playdough.
2 C. flour
1 C. salt
1 T. Alum ( found in spice section of grocery store)
1/4 C. oil. vegetable or baby oil
1 3/4 to 2 1/2  C. of boiling water.
Children can measure, level and mix the dry ingredients. Use a popsicle stick to help teach how to level the flour,etc. Great for fine motor skill development. Put all in a large bowl or ice cream bucket and stir while the water is boiling. Parent or adult has to add the boiling water away from the children and do the stirring here. Food coloring, scented extracts and oil can be added with water if wanted. Water amount may need to be adjusted. It will look soupy at first but as it is mixed for a few min. it will eventually come together. The warm playdough can then be given to children to play with. This is a great sensory experience especially on cold winter days. A little flour put on the table surface first helps with sticking.  Popsicle stick cutters and a garlic press make great playdough tools.  Do not place this dough warm in a ziplock bag as it will get sticky. Let it cool first and then store in baggie or lided container. You may store in refrigerator if you wish but it is not needed. This playdough would keep for 1 to 2 weeks or more depending upon use. I could usually keep it for 2 weeks in a classroom of 25 children using it daily.   A couple of variations you can make are coffee or chocolate smelling playdough..  For the coffee kind just add a couple tablespoons of instant coffee to the water and no food coloring.  For the chocolate kind you can omit 1/2 C. flour and  replace  it with 1/2 C. cocoa powder. This smells like brownies.  You can warn children that it won't taste good but they will probably want to eat it.   It won't hurt them if they take a taste but after the initial taste they probably won't want to again.