Monday, January 14, 2013

Place value with base ten blocks

How many of you are obsessed with the new common core standards like I am? I think they're so wonderful, and I can't wait until they are fully integrated into our curriculum in 2014. Yes, I packed my dork card in my wallet today.

One reason I'm so excited about them is because they offer so many opportunities for our youngest students to build foundational math skills. These skills, such as understanding place value, rounding, math facts, and estimating, are necessary prerequisites for understanding algebra concepts later in their math careers. Math is like a toolbox; beginning students collect tools, intermediate students learn which tools to use when and why, and advanced students must determine which of these tools to use on their own. More often than not, students discover that there is more than one way to figure out a math problem. And that's JUST how math is supposed to be!

One of the most important foundational skills is understanding place value. The value of a digit changes depending on the place that it is in. For example, the digit 4 is worth 4 if placed in the ones place, but it's worth 400 if the 4 is placed in the hundreds place. This fundamental idea helps students with number concepts later on. What I've found is that students struggle with other concepts, such as 2 digit times 2 digit multiplication and rounding, when they don't fully understand place value.

The first step in understanding place value is to practice making 2 digit numbers with base ten blocks. To do this, I bring out some of my favorite "toys" from elementary school. Do you remember these?

The ones that I use are green and made of foam, but I remember having the blue plastic ones in school. Most students now use foam ones because they're much quieter. To practice making 2 digit numbers, students start by rolling the tens dice and placing that number of ten sticks on their work mats in the tens column. Then, they roll the ones dice and place that number of ones cubes on their work mats in the ones column. We practice counting the tens by tens, and we practice counting the ones by ones. On a whiteboard, we also practice writing out the number in word form and expanded form. And if you really want to get fancy with it, you can even have students practice doubling the number.

My favorite game to play for place value is with a deck of cards. I draw two cards from the deck, and make a 2 digit number. I model how I place the larger digit in the tens place because the tens place makes the digit worth much more than it would be worth in the ones place. I then let the student draw two cards to watch them make a 2 digit number. Once they have the hang of it, we keep adding places until we get to the thousands period. For my fourth and fifth grade students, we work into the millions place. It's fun for them to try to beat my number, and to kick it up a notch, I let them take all of their cards and reorder them to make the largest number that they can.

What math games do your students like?