during math story problems, the majority of my kids had those pop cubes out building our 2 digit numbers from our math problem to add! We just briefly talked about how much more useful this tool would be when building a big number ("You can build it faster," "I can just count by 10s now!".)Īnd low and behold, the very. When they clean up after math story problems, they are expected to make sure cubes are in their groups of 10s. Then, I told them that we would be keeping our cubes grouped this way all year long. At this point, all of my firsties were on the 10's bandwagon! So, I had each group make all of the pop cubes from their group's tub into groups of 10's and they left the left overs as ones.
#Base ten blocks subtraction full#
We did this together and carefully discussed our 8 ones left over and how they do not make a full group of 10. Once the kids discovered that counting by 10's would be faster, I had each student build their 48 cubes by making groups of 10s.
#Base ten blocks subtraction how to#
What else do we know how to count by? (10's) Could we make groups of 10 cubes so we could count by 10's?"
I had already planned for no one coming up with the idea to count by 10's.here was the plan in case that happens to you: "You said we could count by 5's/2's. They help drive our conversation when we are about to make some ground-breaking math discoveries and help make it easier to pull along the others to a deeper understanding. Then, I asked, "Is there another way I could count that would be even faster?" My highest math thinker saved the day and said, "TENS!!!!" Thank goodness for those high kids. We all agreed that was faster to count and more useful. I shared a girl who had broken hers into groups of 5's. I asked, "Is it useful to have to count all 48 cubes by ones? How could we arrange the cubes so they would be useful for counting?" Some firstie responses: "We could count by 2's! Or 5's! Or 10's!" Then, I shared another kid's tower, and we talked about how long it would take to count to 48 by all counting ALL 48 cubes by ones. Last year, I took a suggestion from a Math TOSA in our district and turned my pop cubes into groupable "base 10 blocks." After taking up the base 10 blocks I asked, "How could we arrange the 48 cubes so they would be useful for counting?" Some of my firsties responses: "I keep losing track of where we are!" "I can't see that cube!" Remember, this lesson takes place in September, so the level of understanding isn't as high as it would be if I did this same lesson now! :) But if you want your first graders to understand and be able to add and subtract 2 and 3-digit numbers on their own without your help in remembering a bunch of steps? Yeah, not gonna happen with base 10 blocks.at least not before they understand the base 10 system. If you want to be a teacher that just teaches kids the steps and lets them copy you, then fine. You can pretty much count on your typical first grader, taking away the whole ten rod instead of trying to exchange it for ones and only take away part of it. And if they need to break apart the ten to subtract? Forget about it. That's something that takes a lot of experimenting with counting and grouping objects to understand. As a teacher, I can't just tell them 1 ten rod is the same as grabbing 10 and expect them to understand. And that's really, really, hard to master.
Kids can't actually build their own group of ten, they just have to know that grabbing 1 ten rod is the same as grabbing 10. So, what's the big deal? Why don't base 10 blocks work?īecause they can't be manipulated and changed. We spent most of last year's math leadership class talking about our base 10 system and how important it is for kids to understand base 10 to be able to add, subtract, multiply and divide successfully and with understanding. Because they couldn't use the base 10 blocks to help them solve math problems on their own.well, besides maybe 2 kids out of 25. And they totally got how many rods and cubes to use to build 2 digit numbers-even 3 digit numbers.īut, did they really understand our base 10 system? During our math mysteries time, my kids were super pumped to grab those shiny blue base 10 blocks and then used the ten rods to represent the friend that their math mystery was about, or even ed a ten rod to represent one of something, a tally mark, the number one.Īnd, yes, I spent a good 5-10 minutes every day working on breaking numbers apart into tens and ones with interactive base 10 blocks during Math Wall. You see, the problem was, my first graders were using the base 10 blocks for anything BUT math. "No math tool should ever do the thinking for the kids."Īnd it changed how I thought about math manipulatives.
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