# 1st Grade Number Sense Resources

This is meant to develop understanding of addition and subtraction of 1 and 10. You are given a starting number and and ending number (the relationship between having been determined by the adjustable "Difficulty"). Your job is to get to the ending number by adding or subtracting one(s) or ten(s). Choose a representation to help your thinking and try to find the most efficient pathway.

You are looking at a section of a hundreds chart. Use what you know about the ± 1 and 10 relationships of a hundreds chart to put the numbers in the correct locations. Some numbers won't fit! (Click "Skip" for these.) Check your work as often as you'd like.

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.

This grid goes to 120. Click on the numbers to toggle the colors. Click on an arrow to turn the entire row or column red. Explore 1 or 10 more/less, patterns in skip counting or beyond.

Specify an number, then watch as it goes from a collection of "ones" to groups of "tens." See the various forms of a number to build understanding of place value. Alternatively, specify a number, make it into tens, then break the tens into ones to develop understanding of regrouping. See also "Showing Numbers with Place Value"

Enter any number of hundreds, tens, and ones to see that number drawn in any of three ways. One way of using this is to help students see the difference between a digit and its value. For example, a student might say the number 63 has 60 tens and 3 ones. If you enter that in this applet, you can see a number represented as...

- 60 tens and 3 ones ("How I typed it")
- 6 hundreds and 3 ones ("Standard place value")
- 603 ones ("All ones")

An exploration of +/- 1 or 10 on the hundreds chart. Make a "path" (of up to 50 squares). Your job is to figure out the numbers. By clicking on the square, the number is revealed.

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".

An unmarked number line is provided, with 0 on the left. Students are given a random number (either 1-10 or 11-30/50) to place on the number line (repeated up to 20 times). The goal is not only to place numbers in the right order, but also in the correct relative position (e.g. 2, 3, 8, but the 3 should be closer to the 2 than the 8). Feedback is provided by displaying the correct locations based upon the location of the largest number.

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.

Intended for students to get a sense for "bigness" of numbers. Type in a number to see it displayed in an array. If you wish, enter another number to see a visual comparison.

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.

One or more ten frames appears on the screen (you can adjust this). A randomly generated number of dots flashed, (partially) filling in the ten frame(s). Your job is to say how many dots you saw and how you saw it.

This activity is meant to get students using place value flexibly as they estimate a quantity (randomly generated between 20 and 99). Enter a number of tens and ones to match the given (grey) amount. Once you've matched it, try to think of other ways of making the same amount.

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.