Any who! Estimating is an essential skill in Math. Your best students seem to do this naturally. They whiz through rote practice, conquer word problems, can pick out number intervals for number lines, and pick a part multiple choice answers like beasts. Why? Number Sense. They have it. They don’t have the cutesy poem memorized. They have major math muscles! (Ah!!! She said what?! Wait! Don't stop reading yet! AFTER, your students have a good understanding of the concept, I am all about mnemonics, songs, and poems! )
Number sense has to be built into our students. Most of our students do not come naturally to it. Therefore, it is our jobs as educators to do it daily and effectively. So how can you get estimation and number sense into your daily routine? Here are some ideas and tips…
Tip # 1- DO NOT TEACH THE POEM FIRST!!!! (Forget “5 or more for a little while!” We’ll come back to it, I promise!)
Tip # 2: Teach it with real world objects and situations, first and always!!!!! Here are some ideas...
*Pull out different colored bears, blocks, foam pieces, etc. Then quick! Estimate how many and record your students responses. Don’t let them count! Just guess then you can count together. This is quick and easy and gets them thinking!
*Ask your students… How long do you think __________________ is? Record responses then measure.
*How long do you think it would take us to…
*How much liquid do you think this ______________ will hold?
These activities can be done at each grade level and even in Guided Math groups. Just adjust the measurements according to your standard. Younger grades may measure in hands or to nearest inches. Older grade may estimate to the nearest half of an inch, minute, etc.
(Yes, you can use the candy jar, but don’t let this be your only activity!)
Tip # 3-Number lines, number lines, number lines! Use them! They are your best friends!!!!
I have used clothes pin number lines, students and jump ropes as number lines, number lines on the Smartboard, chalk number lines, vertical number lines, number lines that look like mountains, roller coasters, cities, etc. Number lines that count by 2s, number lines that start at 14, and so many more.
When students can visually see what their number is closer to, they quickly and easily estimate. The more often they practice, the more their number sense grows!
Tip #4- Use Number talks! I know you think, I don’t have time for those. And have you ever tried them? Yes! They are worth the time and effort it takes to develop, I promise. Go on Youtube and watch teachers have number talks. Develop your own routine. It helps in so many ways!!!!
For now, I am going to way oversimplify this process. Give you a very brief overview of what I did in my classroom with great results.
1. Pose a problem on the board or anchor chart. Example- 58 + 61 =?
2. Give 60-90 seconds to allow kids to think over answer.
3. Call on several students to give their sum. Record under a heading with something like “Possible Sums” (Always model great math vocabulary! If you aren’t using it, they won’t!)
4. After several student solutions (no processes yet) I always give/record a “crazy answer”.
5. Next, I ask students to think/pair/share. They should discuss if we can eliminate any answers. They must be ready to prove it! (And no names when it is time to eliminate, just the answer.)
6. Allow students to tell you what they answers they eliminated and why. (You will need to model this routine for them, it will not come naturally at first.) After several number talks, at least some your students should tell you through estimation, a justification that will get rid of an answer or two. And look! You have higher level thinking, students talking and interacting, and you get to walk around and monitor thinking and behavior! (It’s good teaching and looks great on TTESS, just saying.)
Example: Crazy Answer- 15
It can’t be 15.
58 is close to 60.
61 is close to 60.
60 + 60 = 120.
We are finding the sum of two whole numbers. Our sum should get larger since we are joining two groups.
7. Now, cross out any sums that don’t make sense.
8. Allow students to share their processes. I always write down what they are saying step by step.
9. Finally, we solve using standard algorithm.
Tip # 5- Games, Games, Games!!!!!
Play games whenever you get the chance! Kids love them, they are engaging, and competition is a great way to learn! Look at my estimation page for some interactives as well as some printables.
So there you have it! Those are my five tips for incorporating estimation and number sense into your classroom. After I have built in these routines, then I teach with the mnemonics, songs, and poems. But the understanding HAS to be there first.
Do you have a favorite way to teach estimation? Share it with us!!!!