So about the title, ups and downs. Yesterday in 5th grade I had a major flop of a lesson. Ok, here is the gist, I tried following the textbook, (mistake) and the lesson was on front-end estimation with adjustment. This isn't even really a standard that I need to teach, just for the mathematical practices. The students were ok with addition, but when we hit subtraction all I could tell them was do it this way because I said so! I couldn't for the life of me explain it without saying, this is the way you do it, so do it! Does that make sense? The textbook, which for the most part, I really love even said "Make a poster showing the two ways to use front-end estimation with adjustment for subtraction so that students remember." Not how to explain why it works, just have them memorize! UGH!
Here are the examples I used to teach them, which come straight from the book.
I really felt like a failure of a teacher with this lesson! Today when I checked thier homework however, 90% of them had it done correctly thanks to the little "reminder" on the page showing them exactly what to do. Those that still didn't get it, I told them as long as they can estimate the difference by rounding the whole number they would be fine. My problem with the textbook is that if you want front end estimation with adjustment to get an answer closer to the exact amount, why round the "leftovers" to the nearest thousand? For example, why not in the first problem estimate 800-200 and then add 600 to the 2,000? Also, I still can't explain properly why we add the difference of the remainding numbers in the first problem and subtract them in the second.
Today was much better, I was able to effectivly use my second block for practice, remediation and enrichment like I intend to. I'm still not 100% comfortable with the whole stations thing. I have to just have differentiated assignments for them, so sometimes kids at the same table are doing all different things.