2GAboys Posted November 30, 2011 Share Posted November 30, 2011 2/3 x 12 for example (fraction x a whole number). Conceptually my son understands why it is 24/3 and it makes perfect sense then to him just simplify it to 8 wholes but unfortunately ALEXS taught him (not to well I might add) to change the problem to 2/3 x 12/1 and to cross out the 3 and write 1 and cross out the 12 and write 4 and then to multiply the top across and the and the bottom across to get 8. Is there a better way to explain this algorithm better than my thought here? Lay out 12 sets of 2/3s, ask him to focus on just 1/3 out of each set (12) and ask how many wholes can you make with just those 12 and the answer is obviously 4. Ask him to look at how many thirds is left with is 12 which is another obvious 4 wholes-then go back to the alogorithm to multiply the 2/1 x 4/1 = 8. Then we do several of these types of problems with the fraction strips and test the algorithm to see if it works every time. This is my common sense way to teach why this algorithm works-BUT I am not a math teacher and want to run this by someone more experienced. I assume this algorithm is essential to teach and that it lays the foundation for something down the road. I have always taught math conceptually with Right Start-but I am solo on teaching the why of this algorithm. Quote Link to comment Share on other sites More sharing options...
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