# Fun Activities for Subtraction w/ Regrouping?

Discussion in 'Elementary Education' started by S Dubb, Oct 31, 2009.

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Oct 31, 2009

Our third grade team is supposed to hit this concept this week. Most of my kids pretty much have it down, but I have a few that struggle. Rather than just practice and practice the steps, I was wondering if anybody here had any creative/fun ideas for teaching subtraction with regrouping (to the hundreds or thousands).

I planned on showing them exactly why we regroup with base-ten blocks, but that doesn't really cover the "fun" category.

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Oct 31, 2009

True. BUT always keep in mind the value of doing the regrouping with base-ten blocks! Having each student have a supply of hundreds, tens, and ones (flats, longs, and cubes) and actually representing the two numbers being subtracting and physically Taking Away to solve will really help them in the conceptual understanding.

As a 4th grade teacher, I get super frustrated when my students subtract by borrowing and have no clue what they are doing or why they are doing it... thus resulting in too many RANDOM answers that make no sense and they don't even realize it.

So many of my students don't know why you cross a number out and make it go down and then add a 1 next to the other number. They just do it blind and that's where the silly mistakes come in.

One thing I liked that one of our third grade teachers did was put it into context of borrowing sugar for a cake they are baking.

So if you are doing 325 - 127... the ones place doesn't have enough cups of sugar... so she goes next door to the tens and borrows a box, so now she has 10 cups. But now since the tens gave away one box (a ten) the tens no longer have enough for her recipe... so she goes to the hundreds and borrows a case (which becomes 10 boxes) and now she has 11 boxes and can easily use 2 for her recipe.

The benefit of this story is that if you do a problem like 307 - 138.. when you borrow the first time, you can't borrow from the tens because they have no sugar. BUT instead, the tens decides to help out and talk to her neighbor the hundreds.. gets a case... and then gives a box to the ones. (as if the ones can only talk to the tens. and the tens can only talk to the hundreds. so the ones can not just talk to the hundreds).

You could also do pats of butter, stick of butter, and box of butter .. so it sort of mirrors cubes, longs, and flats.

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Oct 31, 2009

oh I LOVE the sugar idea!!!

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Oct 31, 2009

I agree 100% about the concept of teaching why it's done rather than just teaching them how to do it. I still plan on doing the base-ten blocks, but I was hoping to add to it.

I like the sugar idea as well. Question though...what happens when you have something like 305 - 127 instead of 325 - 127? Unless I read your description wrong, you said to borrow from the tens and then go straight to the ones and work from there. THEN work with tens borrowing from hundreds. No problem with that, except when the tens column has zero to start with (on top). Do you teach them to borrow twice (once from the hundreds to tens, then from the tens to the ones)? I've done this before and it's worked just fine, but I'm afraid if I teach it two different ways then they'll get confused. Did that make sense?

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Nov 1, 2009

See my 2nd to last paragraph. You would explain that the ones can talk to the tens, but the ones can't talk to the hundreds (maybe she doesn't know her phone number.. lol). So when the ones goes and asks the tens, the tens says she can't help. But, the tens tells the ones that she will ask her friend the hundreds. The hundreds helps the tens, and then the tens passes some to the ones.

7. ### czaczaMultitudinous

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Nov 1, 2009

Have you ever played 'Race to a Flat' with the base 10 blocks? You can do the reverse and play 'Race to Zero' in which the kids start with a 'flat' (100 block) and roll a dice to subtract, exchanging the base 10 blocks each time to show their new total.
Here's a link for 'Race to a Flat': http://www.etacuisenaire.com/pdf/40975_sample.pdf

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Nov 2, 2009

Whoops, I must have completely missed that part! Thank you.

9. ### LinDollNew Member

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Jun 10, 2011

Shaving cream fun

One really fun way that I practice subtracting and many other math concepts is by doing it is shaving cream. It sound crazy and can be if you don't first establish the rules. Before we get started I tell the students exactly what I expect of them. I tell them that if they get out of their seats, put the shaving cream anywhere it should not be, draw things other than what we are practicing, or anything else of that nature they will immediately loose their chance to play. As soon as that happens you have the student clean up their mess and give them a blank page to follow along with. They are doing the same problems, but aren't having as much fun. It usually takes one student one time and that's all it takes for the year. I show them different problems to solve in the shaving cream. They create a work space by spreading the cream out. They write the problem and solve it. You walk around checking for correct answers. This give the more advanced students a fun outlet. It provides a bit more time for you to spend with the ones who are struggling quite a bit. If you don't mind getting your hands dirty you show them how to work it right their in their shaving cream. After everyone gets the answer or you have spent some time I usually go over it on the board.
It's also a great way of cleaning their desks if you do it somewhat regularly.

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Mar 2, 2012

I just now stumbled upon this post, and I know it's way after the original post! I actually teach 4-5 different subtraction strategies. We learn counting back, counting up, borrowing, tens & ones (pictures of the blocks), and mental math. For mental math you add the same number to the top and bottom number in your problem so that the bottom number ends in a 0. If you originally had to borrow 1 time, you wouldn't have to borrow at all. If you originally had to borrow 2 times, you would only have to borrow once. My school feels it's really important to teach a variety of strategies because all of our brains think differently about math. We do put a little more focus on borrowing and tell the kids that this is the best strategy for when you get really big numbers though.

One fun thing I have made to help make borrowing more fun is a riddle scavenger hunt. I gave them a riddle like "Why didn't the elephant want to go on the computer". Then I made subtraction problems and assigned words to each number answer. I wrote the answer on a note card and the word for the riddle's answer on the back. The note cards then got pinned up around the school's hallways. The kids the had to solve subtraction problems. Once they got their first answer, they went in the hallway to find the same number on a note card. Once they found it, they flipped the card over and wrote down the answer. By the end they had the riddle finished and my kids had a lot of fun searching around the school.