Sorting is a pre-math skill that allows children to notice the differences between objects, and to group objects together based on common attributes --- a skill that is useful in skip-counting and multiplication, for example. To provide practice with this pre-math skill, have your child help you sort the laundry. Before doing the laundry, have your child help you place the clothing into piles based on common colors. After doing the laundry, sort through the laundry and have her sort shirts with shirts, pants with pants, socks with socks and so forth.
Practice addition skills while making your grocery list and looking through a store circular. Provide your child with a store circular and explain to him that you need him to help you calculate the total of your grocery bill. Tell him the items that you want to purchase and instruct him to look through the circular and write down the prices of each item. After writing down the prices, have him add them all together to find the total amount of money that you'll need to purchase the items on your list.
Have your elementary child help you cut a pie and practice fractions at the same time. Set out an uncut pie and tell your child that you want to serve the pie to each member of your family and don't want any leftovers; ask him to tell you how many pieces the pie should be cut in to. Ask more complex fraction-questions, such as, "What fraction of the pie would be left if Dad didn't want a piece?" or "What fraction of the pie would be gone if only two pieces were eaten?" Think of different ways to divide the pie and ask your child different types of fraction-related questions.
Search for symmetrical objects in your home with your upper elementary or middle school student. Draw a variety of shapes on paper --- a heart, a circle, a square and a rectangle, for example. Discuss what symmetrical means and show your child how to draw lines of symmetry on each of the shapes. Draw more complex shapes and ask her to identify if they are symmetrical or not. Search around the house for pictures or items that are symmetrical. Look in the newspaper, in magazines or in the refrigerator, for example.
Provide high school students who are learning geometry with an activity that helps them relate the subject to real life. Review a list of geometrical shapes and terms with your child; parallel lines, rectangular prism, rhombus and arc, for example. After discussing the terms, send your child into the neighborhood or to the store with a camera and instruct her to take pictures of real-world items that demonstrate different geometrical shapes and terms. For example, she may take a picture of double street lines to illustrate parallel lines or an orange street cone to illustrate a cone. Print out the pictures and encourage your child to share how they demonstrate geometry.