Rounding can be a difficult skill for second graders. They get hung up on the skill rather than understanding why the concept is important. Developmentally, rounding and estimating is a challenging task for many children. Rounding and estimation are higher level thinking skills that require students to be able to conceptualize and mentally manipulate numbers. Instead of just adding or subtracting, they actually must analyze each number and determine whether they should round up or down depending on that magic number of 5. Then they are offered another challenge; round to the nearest one, ten, hundred or thousand or even more.
Rounding is a way of simplifying numbers to make them easier to understand or work with. Rounding can be used when an exact number isn’t needed, and an approximate answer will do. In real life, rounding and estimation are part of our everyday experiences. When you’re shopping in the grocery store and trying to stay within a budget, for example, you estimate the cost of the items you put in your cart to keep a running total in your head. When you’re purchasing tickets for a group of people or splitting the cost of dinner between 8 friends, we estimate. If students can apply this skill to these type of everyday experiences, we know they have not just learned the skill, but understand the concept.
For students, estimating is an important skill. First and foremost, we want students to be able to determine the reasonableness of their answer. Without estimation skills, students aren’t able to determine if their answer is within a reasonable range. Second, we want students to be able to use mental math to more quickly arrive at a reasonable solution. If students don’t understand the number sense behind rounding, no matter what number they underline or look at, it won’t be solid conceptual understanding.
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