Basically I first taught the how to measure.. When they could recognise the diference between T. and t. ( for teaspoon ) and 1/2 and 1.4 cup, things like that... I taught them the proper names of all appliances, and tools,, ( I.E. toaster vs. toaster oven, convection oven, ladel, spatula, things like that,, then bought them each a cake mix and let 'em go. When they show an interest is when I started teaching them.. Now my two older kids have dinner night when they each have a turn making dinner, ( no, not fish sticks and fries,, usually a pot roast dinner w/ homemade rolls or something,,) and we also have an 8 yr. old special needs who'se showing an interest in cooking.. Since she's VERY delayed we have her help out and go through the steps with her,, but she knows the difference between a wire wisk, and a mixing spoon, a cooking sheet, a bundt pan, etc... and does very well though she does not know how to read.. she still remembers how much of what to put into a cake mix, or she can do pancakes from start to finish.. Basically continue what you are doing by allowing them to help in the kitchen.. then move them on to more challenging things as long as they understand the danget behind it all and stay alert to it.. ( like no fingers in the mixing bowl while the mixer is going, no metal in the microwave, etc.
Good luck and I hope this all helps.