Chapter 1: Probability and Percent

What This Chapter Is About

This chapter has three big parts.

First, we learn about probability.
Probability tells us how likely something is to happen.

Next, we learn about fractions, decimals, and percents.
These are all ways to show part of a whole.
We learn how to change one into another.

Last, we solve problems with percents.
We learn about discounts, tips, taxes, and interest.

Why We Start With Probability

We start the year with probability.
It helps us use math to think about the real world.
It also helps us talk and work together in class.

Fractions, Decimals, and Percents

We will practice fractions, decimals, and percents.
We learned about these before.
Now we get better at them.

A fraction, a decimal, and a percent can all show the same amount.
They are all about a whole thing.

We will also put fractions in order.
Some fractions are positive.
Some fractions are negative.

Solving Percent Problems

At the end of the chapter, we solve percent problems.
We learn about:

• Discounts (paying less money)
• Interest (extra money you earn or pay)
• Taxes (money paid to the government)
• Tips (extra money for good service)
• Percent increase (going up)
• Percent decrease (going down)

New Words We Will Learn

• Chance
• Decimal
• Experimental probability
• Fraction
• Frequency
• Outcome
• Percent
• Probability
• Ratio
• Theoretical probability

What We Knew Before

We already learned about ratios.
A ratio compares two things.

In this chapter, we only look at part-to-whole ratios.
Probability, fractions, decimals, and percents are all part-to-whole.

We already used addition, subtraction, multiplication, and division.
We used them with fractions and decimals.
We used number lines and pictures to show them too.

Last year, we put positive and negative numbers on a number line.
This year, we will start doing math with negative numbers.

What Comes Next

This chapter is just the start of probability.
We will learn much more about it later this year.