# 1.4 Numbers to 99

## Unit Goals

• Students develop an understanding of place value for numbers up to 99.

### Section A Goals

• Add and subtract multiples of 10.
• Represent the base-ten structure of multiples of 10 up to 90 using towers of 10, drawings, numbers, or words.

### Section B Goals

• Add and subtract multiples of 10.
• Represent the base-ten structure of numbers up to 99 using drawings, numbers, and words.
• Understand that the two digits of a two-digit number represent amounts of tens and ones.

### Section C Goals

• Compare 2 two-digit numbers based on the values of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <.>

### Section D Goals

• Represent two-digit numbers in different ways, using different amounts of tens and ones.

### Glossary Entries

• category
A label that tells how objects in a group are alike.

• data
Information about the things or people in a group.

Example: If you have a box of colored pencils, then the lengths and colors of each of the pencils are data about the pencils in the box.

• difference
The result when one number is subtracted from another.

• estimate

To find a value that is close to the correct value.

• greater than

63 is greater than 32.
63 > 32

• less than

32 is less than 63.
32 < 63

• sum
The total when two or more numbers are added.

• survey
A way to collect data using a group of people answering the same question.

• teen number

A number with 1 ten and between 1 and 9 ones.

Example:
Fifteen is 1 ten and 5 ones.