Estimation is Key

First Day of summer school.
This morning, I snapped a picture of a portion of our school parking lot. My intention: use it as the daily estimation question included in the warm-up.
Q: How many total parking spaces are in the parking lot?

We did our warm-up. I first asked for numbers that were too low and didn't make sense. Then too high. Finally, I asked for their estimates, but didn't validate any responses. We then jumped into our lesson for the day: ESTIMATION.
Opening the lesson, I asked my students to think of one good thing and one bad thing about estimation. Here's what they listed.

  • Doesn't have to be correct
  • It's easy
  • Can be made mentally
  • It's an educated guess
  • "It's free! It doesn't cost you anything." (Oh, I added that one)
  • Not precise
  • Could be wrong
After comparing the pros and cons, the good guys won! Estimation FTW!
It gives anyone a chance to cast an answer based upon specific information. It's a starting point. It keeps your number sense in check. It allows the brain to think abstractly for a brief moment. It's free!

We went outside and delegated the work. Students counted staff, reserved, preschool, handicap, and ordinary (unlabeled) spots. We got a total of 141 parking spaces. One kid was two away with 143 as his estimate. Go figure. Another kid was in the five hundreds. Go figure. After the empirical data produces the answer, we always circle back to our original estimates. It's important for students to see the difference so they can improve their number sense and estimation skills for next time.

Tomorrow, we extend the lesson: convert those itemized numbers into percentages in order to make a pie chart of the allocation of parking spaces.

Check it: Steve Leinwand Case 4: Number Sense
He hits some great points at 2:25. It's worth watching the whole thing in my opinion.
Steve exclaims about estimation, "We need to build that into ALL the things that we do!"

Think how many times a day we estimate:
Time to get ready in the morning. Time to get to work. How long is this darn red light? How long before I get my cup of coffee? How many? How many? How many?

Please share with me!
What can I do to make estimation better with my students?
How do you use estimation effectively?
How do your students benefit from it? (or not)
What are some other daily estimations you make?