The Principle of Adding Like Units
The Principle of Adding Like Units is a Grade 4 math skill in enVision Mathematics, Chapter 9: Understand Addition and Subtraction of Fractions. Students learn that fractions can only be directly added when they have the same denominator, just as you can only add like units in other areas of math.
Key Concepts
To add quantities, they must have the same unit. For example, we can add 3 apples and 2 apples to get 5 apples. In fractions, the denominator tells us the fractional unit (e.g., fourths, eighths). We can only directly add fractions that have the same unit, meaning they have a common denominator.
Common Questions
What does adding like units mean in fractions?
Adding like units means you can only directly add fractions when they represent the same-sized pieces, i.e., they have the same denominator. Just as you add inches to inches, you add eighths to eighths.
Why can you only add fractions with the same denominator?
Fractions with different denominators represent different-sized pieces. You cannot add pieces of different sizes directly, just like you cannot add meters to feet without converting first.
What is the principle of like units?
The principle states that you can only combine quantities that measure the same unit. In fractions, the denominator defines the unit size, so both fractions must share the same denominator before adding.
How do you add fractions with the same denominator?
Add only the numerators (the number of pieces) and keep the denominator the same (the size of pieces). For example, 3/8 plus 2/8 equals 5/8.
What chapter covers the principle of adding like units in enVision Grade 4?
The principle of adding like units for fractions is covered in Chapter 9: Understand Addition and Subtraction of Fractions in enVision Mathematics Grade 4.