Easy Addition, Easy Subtraction and Algebra
Some word problems that sound like they are examples of Easy Addition are in fact examples of Easy Subtraction. Here is an example:
Suppose that you have 3 snakes and that someone gives you some more so that now you have 7 snakes altogether. How many snakes were you given?
Click here to watch
Rose as she realizes that
this is a subtraction problem.
Click here to see
Eva solve a problem
just like this one, but in a very different way.
Similarly, some Easy Addition word problems sound like they are
examples of
Easy Subtraction. Here is an example:
Suppose that you have some snakes and that after 3 of them slither away you have 4 snakes left. How many snakes did you start with?
Click here. to download (in PDF format, in a new window) a detailed discussion of problems like these and some thoughts on how to teach children to solve them.