Number Sense to 100 and 1000

The focus of this unit is on reading and representing numbers. Students are expected to be able to read, write, and represent numbers in a variety of different ways. A good understanding of numbers helps students to be able to think more flexibly about them and how they can be broken apart and built in different ways. This is an important prerequisite for being able to efficiently perform operations like addition, subtraction, multiplication, and division.

Topics covered include:

• reading and writing 2-digit (grade 2) and 3-digit (grade 3) numbers in words

• reading and representing 2-digit (grade 2) and 3-digit (grade 3) numbers in a variety of ways with hands-on materials, pictures, coins, expressions, and numerals

• determining if a number is even or odd (grade 2)

• exploring number relationships and partitioning (breaking apart) numbers and representing partitions as expressions

• comparing numbers and putting numbers in order in a variety of ways using number lines, number charts, and other models, and using benchmark numbers, and comparing numbers using the symbols <, >, and =

• estimating quantities (and justifying estimates) less than 100 (grade 2) or 1000 (grade 3) by comparing the set to a referent (a given amount of known quantity) and by selecting an estimate from among three possible choices 

• understanding the concept of place value in 2-digit (grade 2) and 3-digit (grade 3) numbers

• representing numbers using hands-on place value materials

• representing the place value of numbers in a flexible way (e.g. thinking about 327 as 32 tens and 7 ones or as 3 hundreds and 27 ones)

Some Ways to Practice at Home:

• As you encounter numbers when you are together with your child (at the store, on TV, in the newspaper, online, house numbers while driving, etc.) have your child read the number to you. Alternatively, you say the number and have them write it.

• Ask your child to solve number riddles. You can incorporate a number of concepts into these (place value, comparing, etc.). For example:  I am a 3 digit number. I have 4 hundreds and I have a 6 in the ones place. I am greater than 450. What number could I be? Try including different representations of numbers in your riddles. For instance: I am a number greater than 500. I have 47 tens. What number could I be? How many ones would I have?

• Give your child a number and ask them to tell you a number that is greater or less than that number. Or give them a list of  numbers and have them put them in order from least to greatest, or greatest to least.

• Ask your child to estimate an amount (like how many beans will fit in the cup, how many people at the hockey game, how many candies in the bag). Talk about what numbers would be reasonable (10 beans in the cup is probably not reasonable, nor is 900). Give them a referent by showing them what 10 or 100 of that item looks like and then have them refine their estimate.  Don’t focus on trying to get the exact number, focus on making a reasonable guess.

• Play the Place Value Game. Your child should know the rules, because we played in class. Prepare a set of cards with numbers from 0 to 9 (or use a regular deck of playing cards, take out the face cards, use 10 as 0 and Ace as 1) and have an area (mat drawn on paper) for 4 cards (hundreds, tens, ones, and reject, for grade 2, use only 3 spots and eliminate the hundreds spot). Take turns picking cards and placing them in one of the spots on the mat. When both players’ spots are full, the one who made the greater number is the winner. 

•  Work with your child to solve problems involving numbers.

 For example: 

The bike you want costs $327. If you earn $10 each week, how long will it take to get enough for the bike? 

– P.S. Don’t jump to long division or moving decimal points for this one, think about breaking the hundreds into tens and counting how many tens are in the number.