How to Teach a Sense of Larger Numbers through Estimation

This is a guest post from our friend Brandi, an elementary teacher who will share a fun classroom activity for promoting awareness of large numbers. If you are interested in contributing to the Happy Numbers Blog, please see our guidelines here.


A Guessing Jar is one of my favorite activities for promoting number sense and an awareness of how large a number is. I love that it can be filled with anything small or large and right away we have a number activity that is unique every time.


In order to allow everyone a chance to bring in something for the jar, I have each student bring in an item for the jar during their birthday week. Candy is always a favorite but it’s up to each child. I have had everything from candy to cotton balls to Legos. The first thing my students do is make their individual estimates. At the beginning of the year their guesses fall into a wide range of way too small to way too large, but by mid-year or end of the year the guesses are becoming more and more accurate.


We work together to line their guesses up in order from smallest to largest so that we can easily discard guesses as we discover which ones are inaccurate whether too low or too high.


I dumped out the contents and as soon as my students saw this pile, some were already bemoaning their estimates. We always begin counting together and organizing into piles of ten.


In order to help us look at the numbers, students start recording the important numbers.


I want my students to focus on the grouping of each ten so we circle each ten and label our counting. When we reach 100, we circle it to show that we have one hundred before we continue counting. With this particular item we only had one more ten, but usually there are some ones too.


I love that my students are able to see how many items there are in 110. We are looking right at how large this number is in a concrete way. Now it’s time to look at the closest estimates and determine how far off these students’ guesses were.


This becomes a quick ten-minute whole class number sense activity that we repeat 20-30 times in a year to help students learn to critically think before estimating, gain a better understanding of the relationship between size and quantity and most importantly, help them gain a better sense of counting with bundles of ten.


For some independent practice you will want to give Filling Boxes a try. Filling Boxes is one exercise from Happy Numbers’ large collection of activities under the topic Numeration 21–100. It can be played on a computer or on individual tablet devices. My students are currently using it on iPads during our math rotation time. Here is a look at this game on the iPad:


Students move the apples to fill boxes and once the apples have filled all the boxes possible, the number keys pop up for the student to answer how many total apples there are. You can also have students play this on your Smartboard, directly from your teacher’ account. Here is a look at this game on the computer with a specifically designed Smartboard keyboard:


This is a great way to give more individual practice to students. You will also want to check out the Happy Numbers website for more exercises to help you build young mathematicians. They have a large number of activities and topics that help make mathematics more concrete for K-2 students. Plus you can set up each of your students individually and give them access to the exercises that will benefit them the most. What a great way to differentiate for individual needs and give more practice without worksheets.


Now for next week’s Guessing Jar…How many Tootsie Rolls do you think are in the jar?




Brandi is an elementary educator from Utah. In 16 years of teaching, she has taught everything K-3. She has a Master’s Degree in Education from Azusa Pacific College in California and a reading endorsement. Brandi strives to create experiences where young mathematicians make connections on their own and she also runs The Research Based Classroom blog

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