Common Error When Computing Fractions

Common Error When Computing Fractions

When teaching fractions, we need to watch out for common errors or misconceptions that will automatically led to errors in computation. Students at first, often when given a fraction to add or subtract  will mistakenly add the numerator and the denominator across, for example 1/2 + 1/4=2/6  or 1/4 - 1/2 = 0/2. Students are presenting that the fractions numerator and denominators are recognized as separate whole numbers. When working with fractions, students need to connect the relationship between the denominator meaning that the denominator is merely the number of a whole in which one whole is divided into equal parts, which one whole is divided and the numerator signifies the number of those parts. You can model the meaning of fractions by using food. For example, “If you have 3/4 of an apple pie and give 1/3 of it to a friend, what fraction of the original apple pie do you have left?” Subtracting the numerators and denominators separately would result in an answer of 2/1.  Students should automatically recognize that it is impossible to start with 3/4 of the apple pie, give some of it away, and end up with 2 apple pies. Examples like these help students see why treating numerators and denominators as separate whole numbers is not correct when adding or subtracting fractions.

In 5th grade, we introduce adding and subtracting fractions with unlike denominators. In grade 4, students decomposed fractions with like denominators, so they have been introduced to the skill of adding and subtracting fractions. Throughout my years of teaching 5th grade math, many students come into 5th grade lacking skills and making mistakes when it comes to fractions. Some students add or subtract the numerator and denominator across as if each part of the part was its own whole number. As educators, we need to go above and beyond to break barriers and close gaps to get our students at or above grade level.  This strategy/model works great when working in small groups who lack the concept of what a fraction is.

 

Mrs. Zamora - 5th Grade Math Teacher