How Comparing and Classifying Help Common Core Students with Math

By Christopher Danielson

If your child is in kindergarten, you can help them begin to compare and classify things. This will strengthen their ability in other important areas of Common Core math.

Kindergarteners notice characteristics of things that can be measured. These characteristics are called measurable attributes. Measurable attributes of a person include height, favorite color, shoe size, and bedtime. Not all measurable attributes can be expressed in numbers — favorite color, for example — so students discuss which can and which can’t.

When attributes can be measured numerically, students compare with certain types of questions, such as “Who is taller (or shorter)?” or “Who has bigger (or smaller) feet?” These types of questions call on students to compare people to each other according to different attributes. But be sure to include questions that not only call attention to the one that is greater, but also to the one that is fewer.

Students also compare objects according to measurable attributes with these kinds of questions: “Which is the taller (or shorter) tower of blocks?” and “Does a new pencil have longer or shorter lead than a sharpened one?”

Measurement is also about classifying. When you classify, you put things into categories. Kindergarteners might classify a handful of toy vehicles by color by putting the blue ones in one pile and the red ones in another. They might classify the same objects in different ways, such as placing the two‐wheeled vehicles (bicycles and motorcycles) in one category, the four‐wheeled ones (cars and small trucks) in a second category, and the ones with more than four wheels (large trucks and airplanes) in a third category.

Classifying and sorting are natural activities for young children, and the work is closely related to measurement. Being careful about your sorting means naming your categories. And when you name your categories, you’re paying attention to a measurable attribute of a number of different objects (for example, color and number of wheels in the preceding examples).

Finally, kindergarteners compare the number of objects in each category at the end of their sorts. “Are there more two‐wheeled vehicles or four‐wheeled vehicles?” and “What number of wheels is most common?” are the kinds of questions that kindergarteners can ask after they have finished sorting.