Let's Be Rational

Midterm Study Guide Review

Unit Description

The goal of Let’s Be Rational is to develop meaning for and skill with computations involving fractions. Students should know, understand, and fluently use algorithms for computing fractions with all four operations. Students will be able to decide which operation is appropriate in a given situation. In addition, students will be able to use number sense, benchmarks, and operation sense to estimate solutions to situations as well as using estimation to decide if exact answers are reasonable.

Adding with Common Denominators

1. Add the numerators

2. Keep the same denominator

3. Simplify!

Adding with Uncommon Denominators

1. Find the LCM (Least Common Multiple) or LCD (Least Common Denominator)

2. Create equivalent fractions

3. Add the numerators

4. Keep the same denominator

5. Simplify!

Adding Mixed Numbers

1. Find the LCM (Least Common Multiple) or LCD (Least Common Denominator)

2. Create equivalent fractions

3. Add the whole numbers

4. Add the fractions

5. Simplify!

Subtracting with Common Denominators

1. Subtract the numerators

2. Keep the same denominator

3. Simplify!

Subtracting with Uncommon Denominators

1. Find the LCM (Least Common Multiple) or LCD (Least Common Denominator)

2. Create equivalent fractions

3. Subtract the numerators

4. Keep the same denominator

5. Simplify!

Subtracting Mixed Numbers

1. Turn the mixed numbers into improper fractions

2. Subtract the numerators

3. Keep the same denominator

4. Simplify!

How to Add or Subtract Mixed Numbers

Multiplying with Any Denominator

1. Multiply straight across

2. Simplify!


Note: When multiplying mixed numbers, you MUST change the mixed number to an improper fraction and then multiply straight across.

Dividing with Any Denominator

1. Keep it! (Keep the first fraction)

2. Change it! (Change multiplication sign to division sign)

3. Flip it! (Flip the second fraction)

4. Multiply straight across

5. Simplify!


When dividing whole numbers, you MUST change the whole number to an improper fraction by putting one in the denominator.

What are improper fractions?

Improper fractions a fraction with a larger number in the numerator and a smaller number in the denominator. These fractions are "top heavy."

What are mixed numbers?

Mixed numbers are whole numbers and fractions that make one number.