# 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.**two-digit number**