Estimation 180 as a Number Sense Review

I have been back at teaching middle school for a month now. It has been challenging, amazing, and also so deeply tiring!

Years ago I read that the biggest barrier to high school and middle school is lack of mastery of number sense from elementary school. I've tried lots of things as daily routines to help students close this gap but my favorite by far is an idea I got from 4th cohort Desmos Fellow friend Sarah Furman. Sarah shared that she uses Andrew Stadel's Estimation 180 problems but gives her students a clue that allows them to review a key number sense skill. 

I decided to try it in my classroom and I don't really have words for how amazing it has been.

Here is what I do:
I give them an Estimation 180 problem that is either from Andrew Stadel's amazing website (http://www.estimation180.com/) or one that I created about myself, my family, or my community:

I ask students to write their first guess down. I walk around to get a sense of what they are writing and write a few of their guesses down. I put the few I wrote down on the board without naming students and ask for more people to share. THEY ARE NOT SHY ABOUT SHARING THEIR GUESSES. We talk about any we think are too big or too small. Then I give them what I call the "Mathy Clue." I have them write this down too and any clues I give about it. The clue is a specific way for them to review a number sense skill and some math vocabulary. It might be something like. It is a factor of 65 or it is divisible by 11. Or "the digit in the 10s place is a 4. I sometimes also scaffold to help their guesses. When they shout out height in feet...I help them think about what would 3 feet be in inches? What would 4 feet be in inches? Here is a picture of the template I use. This is just below their Warm Up (or Do-Now) problem that they do when they walk in. 

Then I have them make a second guess before I reveal the answer. Finally they write the answer down and reflect. 

I cannot tell you how much buy in I have from the kids. When I gave today's mathy clue (that the answer was prime), one student made a chart on a white board of all the prime numbers in the range of guesses on the board so he could narrow down his second guess. This kind of thing happens all the time. Students eagerly using math to refine their guess. Magic moments in the classroom. 

There is so much genuine joy and excitement when they get close to the answer! (or get it right!). And even if they don't their answer right they are starting to get better. Their ability to convert between units and have basic understandings of how many units are in something is really starting to improve. So grateful for Sarah for sharing this idea with me and can't wait to see how it continues to develop. 

Updated to add that the original idea was from Louisa Connaughton! Thaks Louisa! (https://mathellaneous.wordpress.com)