Conceptualizing Rounding and Estimating

By Clarence Thompson

In our North Portland teaching group, some of our older kids have advanced beyond the written materials we have published to date, so we are scrambling a bit to provide them with materials appropriate to their age level and to the topics to which they are being exposed in school.  One topic that recently came up is the concept of rounding and estimating, and the usefulness of using rounding and estimating to make it easier to solve problems using the four basic operations.  

Therefore, I have started developing a written unit on rounding and estimating, and I thought it would be good to start with a review of the Base 10 numbering system, and the influence which using this numbering system has on calculations involving multiples of five and ten.  Here is a sneak peak at what I've developed so far. (I'll try to give you more next week...)