4.1 Add and Subtract Decimals (p.76-79)

I. Steps for additin of subtracting decimals
1. Line up the decimal points - add zeros to make the same number of digits
2. Bring down the decimal point into the space for your answer.
3. Add or subtract the digits one place at a time - from right to left
4. Estimate to check (usually by rounding)

II. Ways to avoid mistakes:
1. Make sure you have the digits neatly written in columns with the place values correctly lined up (grid or graph paper is a good way to keep things organized)
2. Make sure you include the decimal point in your answer by bringing it directly down from the problem.
3. Regroup just like when you add and subtract whole numbers.


Check out these tutorials from Harcourt on adding decimals and subtracting decimals.

3.4 Decimals and Percents (p.68-69)

I. Percent means "per hundred"
A. Percentages are another way to talke about having a fraction of the whole or part of a whole
1. If you have all of something you have 100%
2. A percentage is like dividing a whole into 100 equal parts then showing how many of those parts you have out of the 100.

II. Converting a decimal to a percent.
1. Move the decimal point two places to the right
a. this is the same as multiplying the decimal by 100 -> turning the whole from 1 equal part into 100 equal parts
2. Put a percentage (%) symbol at the end of the number

III. Changing a percent into a decimal
1. Remove the percent symbol (%)
2. Move the decimal point two places to the left
a. this is the same as dividing by 100 - turning the whole from 100 parts into 1 part

Try this matching game from Harcourt math.

3.3 Estimate with Decimals (p.66-67)

I. Decimals are fractions of a whole - they have relatively small values
A. It's often a good strategy to round decimals to whole numbers
B. Larger numbers = focus on larger place values: In larger numbers, you can even ignore the decimals and focus on rounding to the tens, hundreds, or larger place values.

II. Methods for estimating decimals are the same as for whole numbers**
A. Rounding
B. Compatible Numbers:
C. Clustering
**To review how to do these check the notes from lesson 1.2

Listen to another teacher explain a few examples on this glog from Ms. Seymour. Scroll down to the examples and click on the play button on the left side to learn through some examples.

3.2 Problem Solving: Make a Table (p.64-65)

I. Tables help you organize information and find or use patterns to solve problems.
1. Make sure you understand what you are being asked to find
2. Organize (and order) the information in a table
3. Look for a pattern or sequence
4. Solve the problem
5. Check to make sure you are answering the original question