The ability to estimate is an important component of having strong number sense. **"Number sense" is a person's ability to understand how numbers and quantities relate to each other. **This can have practical benefits but also huge benefits when solving math problems. A student with strong number sense can determine if an answer is reasonable or not. They can also think flexibly with numbers, which makes computation much easier.

## 1. Marble Estimation Game on __ABCya.com__

My third graders love playing this estimation game in the afternoon while we wait for dismissal. The first game is called __How Many Marbles__ (Grades K-6). In this game, children see a container with marbles. They guess how many marbles are inside the container. The computer will prompt them to make another guess if their guess is too low. Once they make a good estimate, more marbles are added to the container. Since the size of the containers and marbles is consistent, students

## 2. Mystery Number Game on __ABCya.com__

Another online game my students love is called __"Guess the Number"__. In this game, students try to guess the mystery number. Once they enter a guess, the game tells them if the mystery number is greater or less than their guess. These clues are helpful if students understand the concept of "greater than" and "less than" and can think about numbers in relation to each other. They should start with the Easy level: numbers 1-10, and then advance to the Medium level: numbers 1-100. Upper elementary students could tackle the Hard level: -500-500.

## 3. Esti-Mysteries by Steve Wyborney

This activity would be great as a whole class activity or math warm-up. __Choose an "Esti-mystery" appropriate for your grade level__, and then set the PowerPoint in presentation mode. Each challenge includes a picture of a clear container with common objects inside. Students make an estimate of how many objects there are, and then refine their prediction based on clues that are given one at a time. I created a video for my third graders when we were learning virtually. Check it out if you want an example of how __this activity__ works!

## 4. Estimation with Word Problems

By third grade, students are expected to estimate sums and differences. They have to understand that signal words like "about" mean to estimate, and then round each number before solving. This concept is really challenging for kids at first, especially if they are weak at rounding. __I created a set of task cards that involve rounding to the nearest ten with 2 and 3-digit numbers.__ The problems have a fall theme but can be used any time of year. Check out the examples below!

What were your experiences with estimation growing up? I remember we always had an estimation contest with candy corn in our school cafeteria each fall. I always guessed too low...I also remember watching my mom estimate how much she was spending at the grocery store.

Happy Teaching!

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