Mathematical Emphasis
Investigation 1—Working with 100

• Finding and counting by factors of 100
• Recognizing factor pairs of 100
• Using landmarks to find differences between numbers under 100 (the difference between 48 and 100 is 52 because 48 to 50 is 2 plus 50 more is 100)

Investigation 2—Exploring multiples of 100

• Using knowledge about the factors of 100 to explore multiples of 100
• Relating knowledge of factors to division situations and to standard division notation
• Adding and subtracting multiples of ten to numbers in the hundreds
• Solving addition and subtraction problems by reasoning from known relationships
• Communicating strategies orally and on paper through use of words, pictures and numbers

Tips For Helping At Home
Questions To Ask:

• What is the problem about? Tell me in your own words.
• What did you do in class to get started?
• Can you solve a simpler version of the problem?
• What have you already tried? What steps did you take?
• Did you show all of your work?
• Does the answer make sense?
• How do you know your answer is correct?

Helping At Home

• Look for opportunities to estimate quantities at home, especially large numbers.
• Play Investigations games sent home in this unit: “101 to 200 BINGO.”
• Find real life examples of large numbers (newspaper, at home, at the store) to discuss or examine (how many peas in the package, etc.).

Vocabulary Terms

Factor

A whole number that can be divided evenly into another number

Landmark Number

Numbers that are familiar and can be used to solve other unfamiliar problems

Multiple

A mathematical operation where a number is added to itself a number of times

Product

The result when two numbers are multiplied

Mathematics Vocabulary Web site

Mathematics Strategy—Working with 100 Charts

This unit focuses on the structure of our number system through activities involving hundreds and thousands. The use of the 100 chart helps students develop a strong sense of 100 as a landmark number.

As children develop knowledge about 100 and 1000 along with multiples and factors, they develop good number sense. For example, a student with this understanding would look at the problem: 229 + 72 and might solve it in the following ways.

• 229 is one away from 230. 30 plus 70 is 100 so the answer is 300 plus 2 (302) subtract 1 (301).
• You can count up by 10’s from 229 (239, 249, 259, 269, 279, 289, 299) seven times and add two more for an answer of 301.

Source: Investigations in Number, Data, and Space: Landmark in the Thousands. Dale Seymour, 1998.

Mathematics Game—Get to Zero

Materials

One deck of numeral cards

Get to Zero score sheet

Playing the Game

1. Deal out six numeral cards to each player.



2. Players make two numbers with four of the cards. The goal is to make two numbers whose sum is as close to 100 as possible. If a player had a 3, 5, 7, and 9, a player could make 57 + 39 = 96.



3. These addition problems are written on the score sheet for round one.



4. To find your score, find the difference between your total and 100. For 57 + 39 + 96, the score would be 4 because 100 – 96 = 4. Your goal is to get as close to 0 as possible.



5. Put the used cards in a discard pile and deal four new cards to each player.



6. For each round of play, make more numbers whose sum is close to 100. When you run out of cards, mix up the discard pile and use them again.



7. Five rounds make one game. Total your scores for the five rounds. Lowest score wins!

Variation: For students needing a challenge, work with 3-digit numbers. Deal out 8 cards and try to find a sum that is equal to 1000.

Get to Numeral Cards (for printing)

Get to Zero Score Sheet (for printing)