More and Less

We are working on adding and subtracting 10 more and 10 less, as well as 100 more and 100 less. Some of the terminology can be tricky to students when they see it for the first time. We automatically think less means subtract and more means to add. This is not always the case in problems that are describing an unknown number. For example, 77 is 10 more than ______. In this type of problem, we have a "mystery number" that we need to find. 

What do we know already? We know that 77 is 10 more, or 10 greater than this number we are looking for. Therefore the missing number is actually 10 less than the number already given (77). So we must subtract (77-10) to get our answer (67). On a hundreds chart, we can move up one space to subtract 10. 

You should see problems like this on tonight's homework. We will continue to work with these, but please let me know if your child needs extra help.