3rd Grade Number Sense Resources

Start by entering a number that will be the center of the number line. Then enter additional numbers to see how their positions on the number line relative to the center number. Meant to develop understanding of proximity and rounding. (e.g. Start with 500. Enter a few numbers that would round to 500.) Two boxes at the bottom allow you to check the rounding.

How do fractions map to the number line? How big do the numerator and denominator need to be to make it "full"? Is it even possible? Explore some of these questions and many others (like finding patterns in equivalent fractions) with this simple, but powerful applet.

Two similar tools for recognizing and comparing fractions.


A rectangle (representing one whole) is shaded with a random fraction (under 1). Guess the fraction. Additional information is provided after each incorrect guess.

What if we took a hundreds chart and replaced the whole numbers with fractions? Explore this idea by clicking "Add to path," then click on a square to show its values...but try to predict the value first!

Set upper and lower bounds. (For 3rd grade, set the upper bound to 1.) A random fraction in generated between the two bounds, with denominators limited to 2,3,4,5,6,8, and 10. Drag a dot to the correct location on the number line for the given fraction. Feedback provided.

Use this resource to explore various fraction relationships, particularly how fractions can be composed and decomposed and the relationship between improper and mixed number forms. Make predictions about the result of a "little jump" (a unit fraction) and a "big jump" (a whole).

Enter a whole number, and the program will sort it in the Venn Diagram according to the two randomly determined rules. Play along with your students as you try various numbers to figure out the rules. Once you know the rules, add additional numbers to each part of the diagram. Possible rules include: bove or below a certain number; Rounds within 100 to a 10; Rounds within 1000 to a 100; Multiple of 3,4,5,6,7,8,9,10,11,or 12; Prime; Composite; Even; Odd

A random number of objects (between 0 and the upper limit you specify) flashes on the screen. Estimate how many you saw. Then display the picture again, reconsider your guess, and finally see the answer. Designed to develop solid connection between a number and how "big" it actually is.

An updated version of "How Many?" with a new feature: once you see the squares, you can arrange them into groups. Use this to connect estimation and quantity to skip counting. Or use it to have a conversation about multiplication or division.

Meant to help develop the idea of possible rounding outcomes by exploring the numbers on an interval of 10, 100, or 1000. Name numbers on an interval (and predict their location!) or drag a randomly generated number to the correct spot (with feedback on the placement provided).

Enter a whole number (under 1 million) and it will be shown as a bar partitioned along base-10 values. Use this for a visual demonstration of, for example, why 543 > 345, beyond "because 5 is bigger than 3".

Drag whole numbers to the correct locations on a (mostly) blank number line. Feedback provided. Adjust the upper limit for the size of the number and how many are placed on the line.

A different approach to rounding. Based upon the location of the number, predict its value, then predict what it would be rounded to. Start by rounding to the nearest hundred (in Rounding within 1000) or nearest 10 (Rounding within 100). Refine your guess as you learn more. Finish by revealing what the number is. The intent is for students to learn that rounding is based off of proximity to multiples of 10 or 100, not a pattern with the digits. The digits merely reveal location.


Enter a number (up to 1000), then regroup it into ones, tens, and hundreds. See also "Making Tens." Designed to allow students to see lots of equivalent representations of numbers.

Designed to develop a specific strategy when faced with a regrouping problem in subtraction. Specify a subtraction problem, then see that represented on the number line as the distance between the two numbers. Since that is a fixed distance, explore how it can be found by adjusting the minuend and subtrahend to generate equivalent subtraction problems, some which would not require regrouping.

Can we partition a circle the same way we partition a square? This applet allows you to compare the resulting areas of vertical partitions in each shape. Adjust the slider to change the denominator then click the button to see the transformation.

A random fraction is placed on the number line between 0 and the upper limit of your choosing (up to 10). Guess what it is, then click the buttons to provide additional information and refine your guess. When you're ready, see the answer in mixed number form.

A random number (upper limit is adjustable) is generated and placed on a blank number line. Your job is to guess where it landed. Click "more info" to zoom in and refine your guess.