Lobster Legs & Whales Tails

We have moved into our 3rd unit in math and will continue to work on developing a solid understanding of basic operations and place value in the context of problem solving. Our first few sessions have introduced a collection of games and activities designed to provide practice with addition facts to 10 and counting sums of money to 25 cents. The children will also be working on sorting and graphing various ways to classify and compare pictures of sea creatures.

Children will spend a great deal of time posing and solving story problems, counting and comparing sums of money, and practicing addition facts. Behind much of the work, however, is the idea of counting by 2's, 5's, and 10's. sometimes this "skip counting" is done in the context of simple multiplication problems - "7 sea stars, how many arms?" or "4 crabs - how many legs?" or "5 dimes - how much is this collection worth?" Other times, work with multiplies is presented in the form of division problems such as "12 claws, how many lobsters?" or "50 legs, how many crabs?" The central principle that children must grasp in order to handle counting by 2's, 5's, 10's or any grouping other than 1's is that collections themselves can be counted. That is, we can talk about the number of 2's, or 5's, or 10's in a set just as we talk about the number of individual units. For example, half an hour on the clock face can be thought of as 30 individual minutes, or 6 groups of 5 minutes, as delineated by the numbers we actually see on the clock.

This is an understanding that takes quite a bit of time and experience to develop, and is not necessarily indicated by a child's ability to skip-count by rote, to recite the counting by 5's or counting by 10's sequences from memory, or to read and write double-digit numbers. The fundamental context for developing this notion is in posing simple multiplication and division story problems, such as "Ms. Rogers has 3 bags of cookies. There are 5 cookies in each bag. How any cookies does Ms. Rogers have all together?" or, conversely, "Ms. Rogers has 15 cookies. She puts 5 cookies in each bag. How many bags can she fill?"

When working with your child to enhance these math skills, or any math content, always have some sort of manipulatives on hand for them to count and compare. You'll be pleasantly surprised how engaged they will become!