[ellen]

What I've found is most difficult for my children is to decide which two tens or hundreds a number falls in between- they get when they should round up or down, but it is deciding what number that is is the most difficult. We spent a lot of time this year drawing the numbers using base ten blocks. They would draw the number, then the two tens or hundreds. THen we looked at our "roller coaster" to decide which way we need to go. More of my class got it this year than in the past.