I've been working on estimation with my kids.
The whole "reasonableness" issue is kind of hard for some of them.
I also created the following center:
It's an 11-page center where students can use grouping strategies to estimate the amount of objects on each picture card. Click the pic above to get all the details.
Here's a poster I included in the download and you can have it for FREE!
Just click the pic and save!
What strategies do you use for estimation?!