When snack time beckons, use it to work some math on the fly. All you need is a bag of goldfish crackers, a plain sheet of paper, and a pencil. It's time for "goldfish math"!

No goldfish on hand? No worries. You can also use small pretzels, crackers, or fruit pieces if that's what you've got in the snack cabinet. Here are four challenges, easiest first, and aimed at kids in kindergarten through second grade. See which one best fits your child’s level:

• How Many? Tell your child, “Think of a number from one to ten. Show me with your fingers. Now, write how many fingers you are wiggling, and that’s how many goldfish I’ll put on your paper.” After your child writes his number on the paper, place the goldfish next to the number. In this game, you’re reinforcing a basic concept of early math, something teachers call "one-to-one correspondence". This is the relationship between objects and numbers in counting. It's not automatic for kids to relate the numbers they say to the physical objects they represent. It takes practice. Repeat as long as you can stand it!
• Password.” Once you see that your child is fully comfortable with matching numbers and objects, you can move to short “mental math”. Say, “Now I’m going to make two groups of fish." Lay the two groups of crackers on the paper and ask, "How many in each group? How many all together? Tell me the total and that’s your password. You get the fish! " Math specialists call this a “manipulative” activity—you’re using concrete objects to help kids recognize abstract concepts. Don’t hesitate to use small numbers in each pile—this helps build fast recognition and mastery of “math facts.”
• Make a sentence code.” Say, “Now we put it all together. Got your pencil ready? I’m going to make two groups of fish. Write the number for each one. Put a ‘plus’ sign between them, and an ‘equals’ sign after. How many all together? Write it after the ‘equals’ sign. You’re making a math sentence code! Write it and you get the fish.” In this activity, you’re helping your child make a crucial bridge between concrete reality and abstract math symbols for it. It’s almost impossible to practice this too much.
• Move on to subtraction.” Once your child is growing comfortable with addition, it's time to move to subtraction. Show her how these two concepts fit together. First, create a math sentence using addition, for example, lay down a pile of 4 fish and another pile of 3 fish, then a pile of 7 fish. Say "Let's make another math sentence. Take out your pencil and turn this into a math sentence. Where should the 'plus' and 'equals' signs go?" When she's written 4 + 3 = 7, ask if she can use those same numbers to create a subtraction sentence. Show her how either the 4 or the 3 can be subtracted from the sum 7. Then give her some fish to enjoy.  In this activity, you’re helping your child learn that addition and subtraction are related. While automatic recall of math facts is important, it's also important for kids to understand the connection between addends and sums.

If this sounds different from textbook math, look again: it isn’t. What you are doing is supporting and applying key concepts of kindergarten, first, and second grade, topics which underly virtually everything else to come. In fact, teachers use versions of many of these activities in the classroom. When you use them at home, you reinforce more than math: you show your children how learning happens all around and at any time. And while you’re at it, you may even make it through snacktime feeling like you’ve nurtured a young mind without losing your own!