Don’t Underestimate the Power of Estimation

The power of estimation for my students comes down to two things. First, the estimation activities I recommend, namely Andrew Stadel’s Estimation 180 and Steve Wyborney’s Esti-Mysteries, involve real-world objects, or realia. When students utilize these resources, they’ll observe anything from candy corn to soda cans and vases to bacon in a frying pan. 

Additionally, these estimation process lessons excite students more than quests to be “correct.” In environments where learning is prioritized, students thrive. Using realia to teach estimation piques student interest and invites unconventional thinking about math. How many times have your students said that today was the best day because they had fun?

Common Core State Standards across most primary grades include estimation as a tool to detect possible errors in calculations and to check for reasonable answers. This is a vital set of skills for all students. If students only encounter estimation as a dry tool to check their work, however, it can become one more tedious activity. 

Math 180

Let me explain why I chose to stick with both Stadel’s Math 180 and Wyborney’s Esti-Mysteries among all the available resources. The main reason is a simple one: process. Both Stadel and Wyborney prioritize the estimation process through refining mathematical guesses. For example, with the first activity in Math 180, students try to guess Mr. Stadel’s height, then that of Andrew and his wife, and finally their children appear.

Each separate estimation activity follows sequentially with answers revealed at the touch of a button. Since the students gain background knowledge about each person’s height with each estimate, their guesses become more reasonable and accurate. Stadel encourages students to imagine boundaries for their estimations. He uses the phrases “How much would be too little?” and “How much would be too much?”

These questions encourage powerful math talk. After students have considered upper and lower limits, he asks them to make their estimation. Students share their thoughts on how much is too little or too much and why their guess is reasonable in the context of real-life problem-solving. Estimation 180 offers a form that students can use as they make their estimations. The form has columns to record the estimation task, lower and upper limits, an estimate, and the student’s reasoning. I made a simple cover sheet and booklet with a few of these pages for each student so that they have a place to collect all their Math 180 activities.

ESTI Mysteries

When you land on Steve Wyborney’s blog, a banner reads “I’m on a Learning Mission.” I discovered his blog when schools first closed in 2020. There are several different free activities to choose from, like splats (subitizing with base-10 counters), a multiplication course, and my favorite, his “Estis.” Much like Andrew Stadel’s Math 180, Wyborney’s Estis focus on the estimation process.

As students encounter an Esti, they begin with a digital image. They’re asked to make an estimation of how much or how many there are in the image, which could range from a length of ribbon to a number of stones in a jar. As students make an estimation, Wyborney encourages them to evaluate their estimates through five clues. With each new clue, students ask themselves if their estimation is still reasonable. For instance, students may be told in a clue that the answer is odd. They will use math vocabulary like this to ask themselves if their guess still fits. Or, a clue may tell them that the answer falls within a range such as between 20 and 40. In total, Wyborney’s Esti Mysteries will have five clues, each with rich math vocabulary.

For example, in Esti Mystery 213, called “Gobs of Globes,” students encounter these five clues:

• The answer is between 50 and 90.
• The answer is a number in this pattern: 51, 54, 57, 60…
• The answer is an odd number.
• The answer is not equal to 25 + 25 +25.
• The answer includes the digit 7.

What’s Needed

In order to use the Esti Mysteries and Math 180 in your classroom, you’ll need a computer and a presentation device. Wyborney creates two versions of each Esti Mystery with PowerPoint and Google Slides. Students could conceivably work on both independently as assignments in Google Classroom. I have students write their estimations on dry-erase boards while we work on Esti Mysteries as a whole group.

Either way, if you’re looking for new estimation activities to spice up your math lessons, you can’t go wrong with these two resources, and you can estimate that each of the activities will take no more than 15 minutes, perhaps even less, depending on how much scaffolding your class needs. If you aren’t sure where to fit them in, here are some ways I incorporate them:

• Bell Ringer (Stadel’s is perfect since it is one static image).
• On irregular schedule days (PE, band, art, etc.) when you may have a few minutes before a nutrition break.
• As a warm-up to a math lesson.
• In lieu of assessments on Fridays when you aren’t ready to assess but have open math blocks.
• As a thematic integration: Both Stadel’s and Wyborney’s lessons can be done out of order. Stadel has candy corn for a fall theme, Christmas lights for December, and candy for Valentine’s Day.
• Here is a link to a worksheet you can use with Estis, if you prefer that format.

Finally, to find even more great resources on number routine activities that you can incorporate into your instruction, go to Howard County Public School System’s resources, where I initially discovered Math 180 and Estis.