Pre-Algebra Period 1 Wednesday 10-15-08 Chapter 3: Decimals and Equations Lesson Title: Ch 3-1 Rounding and Estimating (pgs 122-126) Pt 1: Rounding Decimals Pt 2: Estimating Sums and Differences CA Standards: Math Reasoning 2.1 and 3.1

Lesson Main Points About Decimals: 1. Working with decimal requires an understanding of how the various decimal places are named. The names for the decimal places, 10 (ten) and 0.1 (tenth) differ by only two letters, but ten is 100 times greater than one-tenth. 2. In the place value system the ones place followed by the decimal point is the center of the system: hundreds tens 1. tenths hundredths Don’t make the mistake of thinking that the decimal point itself is the center (or dividing line) of the place value system

Lesson Main Points About Rounding: In computations with decimals, you often need to use only a certain number of decimal places… When rounding to a particular place, look at the digit immediately to the right of that place… If it is less than 5, DO NOT change the digit in the place you are rounding to and drop all digits to the right of it…. If it is more than 5, increase by 1 the digit in the place you are rounding to and drop the digits to the right of it.

Guided Practice : “Check Understanding” Exercises (pg 125) 1-13 Independent Practice: Classwork- “Practice and Problem Solving”(pgs125-126) 15-49 Odds, (18 problems) Homework: Workbook Ch. 3-1 (pg.21) 1-25 All