I teach 2nd grade and will be observed teaching math. We are learning subtracting 2-digit numbers with borrowing. Any neat ideas for a lesson with that? It has to be 30 minutes long, ugghhhh

Do you have base 10 blocks? If so, I would use those in your lesson and let the students practice with them.

Mama, I also teach 2nd grade, and I suggest doing a lesson on using a hundreds chart to solve a 2-digit regrouping problem. It is fun, and there are so many things you can do with it. (If you haven't already introduced a hundreds chart when you learned addition, you can start by introducing the hundred chart, and how to make one. Help the students see the patterns in it, etc.) You can do races and a team game with it, and students can solve problems in teams of 2 prior to independent work time.

Is it actually still called "borrowing" in your curriculum? I thought most had switched to a more appropriate term called "regrouping." I'd first do a brief review of subtraction without the need for regrouping to reinforce and build on prior background. Are you just introducting the process to students? If so, then I agree, base 10 blocks and some sort of game. First, model the game with a student so that all can play, then allow students to experience regrouping. If you are just introducing, then in 30 minutes you most likely won't get to a pencil/paper problem. I'd spend the time building the concept and having the students practice if it was me.

Mama, If you have tons of experience with base ten manipulatives, then ignore this post, but since your post doesn't say how much experience you have, I'm going to write this anyway. While base ten manipulatives are wonderful, I would not use them for a first lesson if it was being observed, and if I didn't have a lot of experience teaching with them. Some students "get it" right away, but many students are confused (and stay confused) until the 3rd or 4th time you use them. Keeping order with so many small manipulatives in little hands can be tricky if you aren't experienced in doing it. I speak from many years of using these maniupulatives to teach subtraction with regrouping (borrowing) and I can tell you it takes practice to keep it from being sheer chaos in many classroom situations. Second graders will build houses out of them, spill them on the floor, grab them from someone else and start a huge argument, etc. Even if the students are being little angels, if 7 of them are doing it wrong, and you are running around trying to help them exchange units for rods, what will the other 13 or so students be doing? Personally, I save base ten blocks for small group instruction whenever possible. It just saves my sanity. Now if the students have already used base ten blocks for addition with regrouping/renaming (carrying over) or for another activity, then I'd say "go for it." -- but I wouldn't want this to be their first experience. There are just too many things that can (and will) go wrong. Also, with second graders and base ten blocks, I use the term "trading" at first. They really understand "trading" 11 units for 1 rod and 1 unit. (Make sure you know the correct names for each of the manipulatives -- calling them by the wrong name is a big no-no when being observed. Units, rods, flats, and cubes, respectively.)

I know a cute poem my cooperating teacher used that I taught some of my 4th graders who seem to forget to borrow,it's talking about the ones column... More on the top no need to stop ( More on the floor go next door and get 10 more Numbers the same zeros the game Each student made a poster with examples of each

We did this with 2nd graders last year btw I just meant that I also taught it to some of my new 4th graders (this yr) Oh yea we did this after the whole working w/cubes n such

I use this, but we do motions too. They stand and say More on the top (point up) no (shake finger back and forth) need to stop (put hand out like stop sign) more on the floor (point down), go next door, (put hands over left shoulder), get 10 more (wiggle 10 fingers as they bring hands down in front of them again) numbers the same, zero's (make a 0 with hand) the game

I like the poem. I have always used the 3 "B's"-- If the Bottom is Bigger Borrow--I see a lot of my students saying this and figuring it out when we first start learning this.