Math - 2018-19

3.5 - Add and Subtract Fractions

The student will 

  • solve practical problems that involve addition and subtraction with proper fractions having like denominators of 12 or less.


Adopted: 2016

BIG IDEAS

  • So that I can modify different amounts in order to create a product (e.g. doubling a recipe, creating a craft, etc.)

  • So that I can combine distances to find a total (e.g. distances students ran, lengths on a ruler, etc.)


UNDERSTANDING THE STANDARD

  • Proper fractions, improper fractions, and mixed numbers are terms often used to describe fractions.  A proper fraction is a fraction whose numerator is less than the denominator.  An improper fraction is a fraction whose numerator is equal to or greater than the denominator.  An improper fraction may be expressed as a mixed number. A mixed number is written with two parts:  a whole number and a proper fraction (e.g., 3 5/8).
  • When adding or subtracting fractions, an answer greater than one can be expressed as an improper fraction or the equivalent mixed number (e.g.,  3/5 + 4/5 = 7/5 = 1 2/5 ).
  • When adding and subtracting fractions the fractions must represent like size units (e.g., one-fifth added to three-fifths is four-fifths). This understanding builds the foundation for why common denominators are necessary in future work with adding unlike fractions and for work in algebra when adding polynomial expressions.
  • Reasonable answers to problems involving addition and subtraction of fractions can be established by using benchmarks such as 0, 1/2 , and 1. For example, 3/5 and  4/5 are each greater than 1/2, so their sum is greater than 1.
  • Concrete materials and pictorial models representing area/regions (e.g., circles, squares, and rectangles), length/measurements (fraction bars and strips), and sets (counters) can be used to add and subtract fractions having like denominators of 12 or less.

ESSENTIALS

The student will use problem solving, mathematical communication, mathematical reasoning, connections, and representations to

  • Solve practical problems that involve addition and subtraction with proper fractions having like denominators of 12 or less, using concrete and pictorial models representing area/regions (e.g., circles, squares, and rectangles), length/measurements (e.g., fraction bars and strips), and sets (e.g., counters). 



KEY VOCABULARY

Updated: Aug 22, 2018