For the past couple of weeks we have been learning strategies to strengthen our ability to add numbers in our head (mental math). Here's an experiment for you to try! Calculate 5 997 + 3 243 (Don't read any further until you have an answer!). Did you grab a pencil and paper? As adults, many of us were taught how to add numbers by writing them in columns, and then adding and 'carrying' across the columns. Usually, we were taught this was the only way to solve questions like this. But is this the quickest, and easiest, way to add numbers? The students have been learning how 'friendly numbers' can actually allow them to perform addition problems like this in their heads (and with greater accuracy than the traditional algorithm). Looking back at the question above, notice how we could easily make the 5 997 more 'friendly' by adding 3 and creating 6 000? Notice how we also could have simply taken that extra 3 from 3 243 to make it the friendlier 3 240? Now all we would have to do is add 6 000 and 3 240, for a total of 9 240. Much easier (and quicker) than all that carrying involved with the algorithm. On Monday, students were shown the algorithm approach, and were asked how it was the same/different from the strategies we were using. It was interesting to hear the conversations, and it was clear that they understood exactly why the algorithm 'carries' numbers over to other columns. Flexibility in his/her math thinking is one of the greatest skills your child can have. Mental math is one way for your child to demonstrate this!
Here are some photos of our Math Wall charts explaining our discoveries:
Here are some photos of our Math Wall charts explaining our discoveries: