Teaching Subtraction

Last week we got a note from Crash’s teacher that he was having trouble in math. Apparently he was shutting down, not completing his work, not answering her questions. Unfortunately, she told us after the fact instead of when he was actually having trouble.

Anyway, I’m not here to rant about his teacher. I’m a teacher, too. Mistakes are made. I’ve made a few. Like that time I accidentally let a 5 year old go home on the bus instead of making him wait for his mom to come get him. It all worked out thankfully. I’m so sorry that happened.

But this was about a kid’s grade. My kid’s. I know a kid’s mark in 3rd grade isn’t make or break, but if Crash is allowed to slack off now, he’s going to think he can slack off whenever he wants. He does it during chores. He’d rather sit and do nothing for a half hour than take the 5 minutes to get the chore done. He applies this thinking to math. He’s good at math. He’s always earned A’s in math. Why does he shut down then?

Subtracting threw him for a loop. Borrowing regrouping in particular.

[Enter] Teacher dad

I started working with him on borrowing regrouping and he started fighting it.

I won.

Then he said, “I don’t get it”. I knew he was getting it, he was completing problem after problem correctly. “What don’t you get” I asked. “Why does this number (the tens place) go down one but this number (the one’s place) goes up 10.”


This I can do. I ran to the basement and frantically searched the Lego bag . I found a bunch of those flat
1 x 10 pieces and some “one-ers” to fill it up and some extras. Yes. I made ones and rods, ones and 10 sticks. Now I could demonstrate visually why that happened.

After solving a few problems this way, he understood. He learned the lesson.

So did I.

He had been applying his chore attitude to math class.

Just because he’s not getting homework doesn’t mean he’s getting his work all done. Just because the teacher hasn’t sent home notes, made a phone call, sent an e-mail, doesn’t mean he’s getting his work all done.

Be sure to ask questions. Even more important, be sure to ask the right ones. My goal now is not just find out how his day went. My goal isn’t just to find out what he did in school. My goal now is ask if he understood it. Then I’ll make him prove it.

Boy is he gonna hate me for those 20 minutes I make him do math.



31 thoughts on “Teaching Subtraction

  1. Math sucks. I could never understand it, either… But it was probably 50-60% the mathematical concepts (my chemical imbalance doesn’t like equations and algorithms), and at least 40% the teaching method. Despite the fact we live in one of the “most well-educated countries in the world,” no one could figure out, for about a decade, how to teach math to a kid with a learning disorder. Good for you for seizing on the real “teachable moment” — not just to realize what the actual problem was, but finding a way to explain it to Crash that wasn’t “the norm,” and would most likely work. In Montessori schools, they always begin teaching math visually, with counting sticks, blocks, etc., and that method proves to yield higher results of comprehension in younger students. We (as a culture) really need to stop thinking the way we’ve been doing things is the only way to do it.


    • He got the hang of subtracting tens. Today we moved on to hundreds. He’s pretty much got that now. He’s picking up on the pattern that you follow the same steps no matter how many digits are in the problem. He put a pretty good fight. His mom and I put up a bigger one 🙂

      Liked by 1 person

      • I sure hope he looks back and say “Dad thank for being more stubborn than me and teaching me that math”. I’m not counting on it. But one can hope. I’m guessing this is just the beginning of a long road of math practice.


  2. Well done, Daddy Eric! Legos are good for math too and I’m sure you’ve got plenty of those. 😊
    I’m sure he’d be resentful for a bit. Heh!

    On the other hand, Math is an annoying subject – it takes a good and patient teacher to really show how to do it. I’ve always thought I’m terrible at it, flunk it all through school. Until an angel of a teacher came along. Just like that, I “get it” – from an F to a B+. It was amazing! He made it doable. I still don’t like numbers very much (except on my paycheck 😜) and yet I deal with some serious stats throughout my career. Funny that!

    Liked by 1 person

    • I saw a thing somewhere where someone had used Legos to teach fractions using the studs. I just adapted to fit subtraction. Math is one of those subjects that requires practice. Obviously getting angry at someone because they can’t subtract won’t make them want to learn it. By the middle of his practice today he was over being angry. He’d still try to drift into Lala Land, but he wasn’t angry. It’s amazing what the right teacher can create in us or sometimes destroy with the wrong attitude.


  3. I love your Lego approach! Little Man is doing this borrowing math now with three digits. I swear I don’t remember doing that stuff in second grade. I found out via his progress report yesterday that he’s screwing around with reading. His teacher said while he’s above level he’s making no progress this year because his comprehension is low. Um, no. We read higher level stuff at home than school and his comprehension is fine. Turns out he’s being lazy as sin at school, plus rushing through everything so he can finish first and get a computer to play on. Smh.


    • Wait… seriously? Are you sure these two aren’t in cohorts? That’s what Crash is doing. Lazing. Off in Lalaland. Anything but his math. I wish we had progress reports here. We don’t know his marks until report cards come home. Do you read to him at home or does he read to you? Comprehension levels can change depending. Just curious, that’s all.

      Liked by 1 person

      • Little chaches conspiring against us! I love these reports, as they are personalized with what he’s doing in each subject. They don’t do number grades at his school, either, but tell whether they’re exceeding, developing appropriately, or need help.

        Both on the reading. He seems to do about the same either way.


      • I know when I was teaching in VA we did progress reports. We also sent home work every two week so parents could see what they were working on and how they were doing. We didn’t keep secrets from parents. Big thumbs up for parent communication! 😉


  4. I hate math and I blame it on bad teachers from my generation. SO glad to hear he has you to assist him and make it fun! My kids both out -math me these days and I am glad but embarrassed at the same time.


    • LOL I wouldn’t say I’m making it fun. We’re still doing worksheets. I just used his Legos to help him visualize what he was doing on paper. That was the only fun part 🙂 DW had a horrible math teacher one year who totally turned her off math. She’s good at it, but she’d rather not do it.

      Liked by 1 person

  5. We made it a game in our house. The rule is to get to twenty off the top of their heads. I give them a number and they have to tell me as quick as possible how many more they needed to get to 20. My kids still ask to play the 20 game…even though they don’t need to. I’ve made it a bit trickier now I change the number to 100 or 50 or 6 323 🙂 You’re a good Dad.


  6. Only a teacher would have this kind of wisdom, which is why I married one! Great post.
    Sorry that I have been a little absent lately…I’m catchin’ up, albeit slowly So many things happen around here in a week or two…


  7. Love it! I’ve got a slacker, too, & I’m at a bit of a loss since I’ve always been intrinsically motivated to study. Oh well, we’re working on it.

    Oh, and it took me FOREVER to stop saying “borrowing.”


    • I still call it borrowing. Except for addition, then it’s regrouping. I can’t find anything to motivate him. He has 0 desire to better himself in math. So we’re working on it, too.


  8. I always found Maths difficult at school (although I was good at other subjects) but I think the way children are taught now is much better than it used to be. I am a teacher (not Maths) but at secondary level, and had to do some experience in a primary school when I first started training. I noticed straight away that Maths teaching had improved-unless I was just older and had a better grasp of it! #FabFridayPost


    • My son thinks everything should just come to him. He shouldn’t have to practice it to be better at it. Unfortunately, he’s not a prodigy. Math teaching has definitely changed in the last 10+ years. Thanks for stopping by to read!


  9. lol! Wow! Well done Teacher Dad! Great that you have sorted that out so professionally. It is such a cool technique. I’m having a hard time just getting anything out from my boy after school – he would not tell me anything – Na Da – Zero – 0! Oh… will just have to keep on trying. Thank you so much for linking up with us again on #FabFridayPost


    • Whenever I ask him what he did in school he tells me about gym and music. I have to specifically ask, “What did work on in math?” Or, “What did you do in Language Arts? Did you write anything today?” Otherwise he did nothing all day. I’ll have to keep these Legos in mind when it comes time for multiplication and fractions!

      Liked by 1 person

  10. I wish I had to tease it out of my DD She tells me literally everything in every detail for 2 hours after school. I’m not complaining honestly, but sometimes it is exhausting. but then one day it’ll stop and then what’ll I do for entertainment.
    I love lego for maths; it’s got a million uses. especially good for division as well


    • Exactly. Once you get past the fact they’re being used for math instead of building it’s easier to stay on task, too 😉 I can only imagine how exhausting it is to hear about every detail. It’s awesome that she’s willing to share that much without prompting! I have to go fishing for details. Sometimes he bites and fills me in, other times I might as well be casting into the bathtub.


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