Monday, September 17, 2012

Estimation 180

Estimation initiative:
[*UPDATE: has gone live]

Last year I willingly started adding an estimation question to my daily warm-up, inspired by Steve Leinwand, Dan Meyer, and a monthly ASB gag we did a few school years back. Everyday, I greet my students at the door and hand them a 3x5 index card for their warm-up. They get the first 2-3 minutes of class to complete the warm-up exercise and estimation question. The first question reviews the previous day's skill. As for the estimation question, last year I was putting questions that were comparable to fun facts and students had no context clues for making logical estimates. It got silly. Here are some examples:
  • How many miles is the California coastline?
  • How long does an elephant stay pregnant?
  • How many In-n-Out Burger restaurants are there?
  • How many miles from the Earth to the Sun?
  • etc.
Stepping back over the summer and really fine-tuning the goal of estimation (improving number sense), I began using estimation questions that were more relative and provided better context clues. Every chance I get, I use a picture or something inside my classroom that will allow students to make logical estimates. Here's today's (Day 10):

I've had to cover up the bottom half of the screen now because students come in and immediately want to go for the estimation question. They want to come up to the screen and do weird measurements, or ask me factual questions, and they flat out forget about the first question. I don't blame them. It's fun. Once we go over the first question (favorite yes/no), I usually have students give me estimates that are too low or too high and then we "go right at it." "Who thinks they got this?"
Once I get about 8-10 estimates, I reveal the answer and it's so cool to see how the students react. "Ohhhh, I was sooo close." Or "I was way off!" Either way, I ask the student or students who were close to explain their logic. It's fascinating how kids think.
For today's, I snapped a picture of a measuring cup full of almonds (my new favorite snack). Tomorrow, they'll estimate how many are in the jar from CostCo. Estimation should build. The whole first week we talked about height, based off my height. 
Day 1: What is Mr. Stadel's height? They don't need a picture for that.
Day 2: What is Mrs. Stadel's height? They needed a picture for that. 
Day 3: What is my son's height? Another picture.
Day 4: What's the height of a lamppost Mr. Stadel is standing near? etc.
The first four days used my height as a frame of reference. Check out Estimation 180 (Google doc will be replaced with )and you'll see what I mean. My estimation initiative is to begin documenting my 180 days of estimation, simply titled Estimation 180. Seriously, do I need one more thing on my plate right now? No. However, I do this every day and would love to share this stuff and receive feedback. Estimation is important to me. I've already seen student improvement with number sense in just 10 days of school.  
I'm starting small here, but would love to expand this idea: stay tuned. In the meantime, check out the spreadsheet catalog (tab at the top).
[UPDATE: is live. Forget the spreadsheet!]

Number sense,


  1. I'm digging the google doc. I hope you keep this going so I can steal from it.
    I've done a couple of these - one with a guy whose face was covered with clothespins (from Guiness).

  2. I focused on estimation when I was a math interventionist in an elementary school. I had my students guess my age to open a discussion about wild guesses vs. reasonable guesses. It was interesting how on Monday the students guessed I was in my late 20s (which was true at the time). Throughout the week I visited different classes and the estimates increased each day until Friday's class thought for sure I was in my late 40s or early 50s. I couldn't imagine that I had aged so much in five days until it dawned on me that I hadn't shaved all week. It's interesting what an effect that had on students' estimates.

  3. @Nathan: Ewww. Pictures like that give me nightmares.

    That was exactly my thinking with the google docs. So, Stades, get all 180 up there by December.

  4. @Fawn and @Nathan That would be quite the early Christmas gift if I had all of those logged by December. 180 school days my people. Plus, it all depends on which of Santa's list you're on. I'll definitely try and get a stockpile going. Don't hold your breath.
    @bstockus That story is classic. Talk about the use of context clues and how it affected the estimates your students made. My genes have given me a pretty laughable beard. hence why you won't see me with facial hair.

  5. I love the idea of Estimation 180 and would only ask that you consider following up the calling out of estimates by sort of clumping them into “close sets” and having students justify their estimates. Over time you should minimize the “I just guessed” and maximize the amazingly insightful explanations that are likely to arise.

  6. Andrew, this is the bomb! I used the estimation of my height to introduce averages this year take all students guesses and find median, mean and mode. Does that make our guessing more accurate?

    They really liked it.

  7. This is great, and I think there is a neat stat lesson in here as well. If we record student answers each day and look at the dotplots, are there certain estimation tasks which show more variability than others? Do kids tend to perform better on counting-type tasks than measurement-based tasks?

  8. I've been thinking about estimation a lot lately, especially since I did the penny pyramid three act lesson. One thing I noticed about that lesson was that the estimates were really all over the place. Some kids thought there were only 500 pennies. Some were closer to 100 million. I started to wonder where the value is in estimating very large numbers. It's obvious that there is something wrong when somebody says 500 pennies when the real answer is close to 300,000. But what about someone who says 3 million or 30 million? Are these estimates "bad" estimates? These large numbers are difficult to conceptualize, and so, do I care if my kids are off my several orders of magnitude when I ask them to guess big? I'm thinking that estimating is much more relevant when you ask to estimate smaller values - when you have 1,000 or less of something. I'd love to hear if someone has any opinions on this.

  9. Love this! Thank you so much for sharing in Estimation 180.

  10. My cousin recommended this blog and she was totally right keep up the fantastic work!

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