In this particular skill, students should master the ability to round numbers to the nearest 10 or 100, based on their previous understanding and knowledge of the value that digits have in certain positions. Also, their previous work with numbers on a number line aids in students’ ability to visually see the position of a number relative to the multiples of 10 and 100 that surround it.
Understanding the Standard:
- Students’ understanding of this concept is aided with practice manipulating numbers on the number line.
- Students should be familiar with the “rule” of looking at the digit in the ones position to determine if one should round up or round down to the nearest 10. When rounding to the nearest 100, students will look at the digit in the tens position to make the same determination.
- Integrating everyday connections with rounding allows students to make the learning of this skill more concrete. Students can relate rounding to going grocery shopping or to any store and purchasing an item. In this activity, they round to make sure they will have enough money to purchase the item needed.
Questions to Focus Instruction:
- Can students identify the multiples of 10 or 100 that are closest to any given number as it is represented on the number line?
- Can students determine the relative distance of a number within the multiples of 10 and 100 that surround it?
- Are students able to determine whether to round up or round down as a result of looking at the digits that occupy the ones place (when rounding to the nearest 10) or the tens place (when rounding to the nearest 100)?
While not formally introduced in prior grade levels, students have worked with adding and subtracting by multiples of ten. Furthermore, rounding to the nearest 100 when the number is 121, students have used expanded notation (100 + 20 + 1) previously and can "see" the 100, and know it will round to 200 or 100.
At Grade Level:
Students will expand their previous knowledge and apply it to rounding any given number to the nearest 10 or 100.