This is a collection of ten different four-step mysteries where students have to work backwards (if you'll pardon the pun...)
Instead of just taking a number and rounding it off to the nearest hundredth, tenth and unit (which is just soooooo boring and unproductive), the student is given the following clues about a "mystery number"
• When rounded off to the nearest unit, the number is 0.
This indicates that the number could be anywhere between 0 and .499 - it the number was .5 or above, it would round up to 1.
• When rounded off to the nearest tenth, the number is .2
This indicates that the number is between .15 and .24; if the number was .14 or below, it would round to .1; if it was .25 or above, it would found to .3.
There are two more clues, but I think you get the point: this is an activity that makes your students think about rounding in very deep and creative ways. There are ten different decimal rounding mysteries (one sample and 9 more for students to work on individually or in pairs of two), as well as answer recording sheets so your students don't have to mess up the beautiful booklets you made! There's also complete answer keys and an opportunity for students to make up their own booklets.
This is fecking awesome!