Here are some ideas for different concepts/ages:
- Toddlers/Preschoolers at the most basic: Pull up a stool, put your child on top, and start narrating: "See the orange carrot? I have ONE orange carrot. (add one) Now I have two orange carrots. One. Two." (make sure you point to the items you're counting off) You can do this with anything: plates, fruit, cups, meatballs, noodles, grains of rice,.....
- Toddlers/Preschoolers, level 2: "How many grapes are on your plate? Let's count them together..." While you are baking or doing any kind of cooking that requires more than one measuring unit, say something like this, "I need 2 cups of sugar. Count with me. One. Two."
- Preschoolers/Kindergartners ready for basic addition/subtraction: "Let's see.... You had 5 grapes and you ate 1. How many do you have left?" Or, "I need two cups of sugar. There's one. How many more do I need?" (just add 1-2 items at a time)
- Kindergartners/Early Elementary, basic addition/subtraction: "I need five cups of sugar. I just put in two. How many more do I need?" (basically, you start adding/subtracting more than 1 unit)
- Kindergartners/Early Elementary, counting by multiples: "How many blueberries are on your plate? Two, four, six,..."
- Early Elementary, ready for basic multiplication/division: "We have five people in our family, and we have 10 muffins. How many muffins does each person get?" (Kids have a vested interest in this kind of math--they want to make sure everyone gets the same number because fairness is BIG.) Or, "we have five people in our family. If everyone wants two tacos, how many tacos should we make?" As with adding/subtracting, start with small numbers (like times two) and move up.
- Elementary (and even middle school), practical application: Wow--when you get to multiplying and dividing fractions, if your child has spent some time with you cooking, he or she is ready to halve or double recipes! Talk about practical application, folks. Tell little Johnny that you want to make a double recipe of chocolate chip cookies, but he has to help you figure out how many chocolate chips, sugar, etc. you will need....
- Elementary/middle school, conversions: Some ratio action here! Try handing out only a 1 teaspoon measuring spoon (b/c doesn't that seem to be the way it goes when you're in a hurry and everything else is dirty?). Then, make an entire recipe, converting all the partial teaspoons and tablespoons into rough units based on your one teaspoon. If you're baking, pick a small measure so you won't have to worry about fractions of the one utensil. If you're cooking, you can eyeball a "half teaspoon" of some spice sufficiently.