Fraction Kits: Subtracting Fractions with Unlike Denominators





Lesson Plan: Fraction Kits: Subtraction Mixed Numbers with Unlike Denominators


Process: Students will use models to visualize subtracting fractions, and understand how the models relate to the algorithm.
Content: Students will learn how to subtract mixed numbers with unlike denominators.


Fraction kits and math journals for each student
Warm-up problems on overhead
Student homework
Exit card

Motivator (5 minutes):

Instruct students to take out their fraction kits, math journals, and homework.

Independent practice (10 minutes):

Instruct students to use fraction kits to complete warm-up problems. Circulate and help as necessary.

Model instruction/check for understanding (40 minutes):

A. Have student volunteers explain how to complete warm up problems using magnetic fraction kits.(10 minutes)
B. Introduce the algorithm for subtracting mixed numbers (1. subtract whole number, 2. find the least common denominator of the 2 fractions, 3. find equivalent fractions of the same denominator and solve the problem). Go over selected homework problems, using both the fraction kits and the algorithms, calling on volunteers to assist.(30 minutes)

Regroup/Summarizing (5 minutes):

Have the students review the algorithm as written in their math journals

Closure (10 minutes):

Have students complete exit card.

Back to Top


Click here to see my university's supervisor's comments on this lesson.

Back to Top


The assessment for this lesson was an exit card, with two mixed number (unlike denominator) addition problems, and two mixed number (unlike denominator, no regrouping required) subtraction cards. From these exit cards, I was able to divide the math class into three approximately equal groups to further instruction the next day. Those who could successfully complete both addition and subtraction problems were given enrichment problems (word problems involving mixed numbers)to work on as a group. Those who could successfully add, but not subtract, were given subtraction problems to work through, as a group, using their fraction kits. I did guided practice with those who could not navigate either type of problem (usually because they still could not provide equivalent fractions with the same denominator for each mixed number). In this case, my assessment tool guided my teaching practice the next day.