# Second Grade Math Warm-Ups: Week of October 12-16, 2015

This week we began a new unit on adding and subtracting within 100 (which is actually a unit we had last year, as well, so should be something that we remember.ย  Should…time will tell if that’s true. LOL ๐ ).

This time around we’re focusing more on making sure mathematicians are flexible and can show their thinking in more than one way.ย  As with last time, we’ll also make sure they can choose a strategy appropriately based on the numbers (rather than just which strategy the like best or is easiest for them), and we’ll also continue to work on being clear with our communicating our mathematical thinking.

Here we go!

The first strategy we worked on for this unit is called HTO, or hundreds/tens/ones.ย  Yeah, it’s kind of an obvious name for what they are doing, so I guess it works. ๐

Each kiddo has a workbook where we’re showing our thinking, and I had to share what Emily’s looked like after I taught this strategy.ย  She kind of liked it. ๐

ย Here’s more about how that strategy works:

First you mark the first number on the chart (98) and then add on tallies to show the second number (31). Then look to see if you can find any tens or ones you need to move over to the next column. Finally, add down the columns to find your answer.

Ok, so this post is a little misleading, because that was the only warm-up I have to share.ย  The rest is more from what we did in our conversations in math.ย  Hope that’s ok. ๐

On Friday, we started another strategy that is Adding on the Numberline (and actually using another strategy called Circle/Split/Add):

We still have a strategy or two to teach, and then we’ll just practice them until they’re solid.ย  The thing I have to keep reminding kiddos (especially those that are focused on being RIGHT and being FAST) is that this unit is as much as communicating and being flexible as it is about finding the right answer (although, OF COURSE that’s also expected. ๐ ).