Rounding can be a very challenging concept for many students. Most of the time students try to memorize the rules: if the number to the right is less than 5, round down; if it is 5 or greater, round up. This is a good rule if students are rounding a bunch of numbers on a worksheet for rote practice but not when they are trying to relate rounding to estimating or real-world concepts.
We really want students to see the entire number and how that number relates to other numbers near it. Increasing children's understanding of rounding will develop their number sense at a deeper level. It helps for children to make connections to numbers and see logical progression between numbers. Below are several rounding games/activities to play with your children to develop their rounding skills and build their number sense.
1. Number Lines: All rounding concepts should begin on a number line. Children should draw a number line to visually see which landmark numbers the number falls between. This way they can "see" which 2 numbers they are choosing from. Below is an example:
2. Rounding Dice: Depending on age and ability, roll 2, 3 or 4 dice to make a 2-, 3- or 4-digit number. You can use different colored dice to represent different place values; for example blue is the ones place, red is the tens place, and white is the hundreds place. Or children can create whatever number they want. Have students round their number to the nearest tens, hundreds, or thousands. If they need the number line from above, they can use that as a reference.
3. Rounding Backwards: Flexibility is extremely important in math and is a true sign of strong number sense. Say or write a number that is rounded or a multiple of ten; for example, 90, 460, or 1,300. Children can use digit cards or write a number that when rounded will be rounded to the number you said. So if you say "460," they could create several different numbers such as: 457, 459, 462, or 464.
4. Matching Rounding Game: Using index cards, have children write 2-, 3-, or 4-digit numbers on each card (about 10 cards total). Then, round each number and write the rounded number on another 10 index cards. Mix up the cards and place them face down. Picking two cards at a time, play a matching game until all the cards have been paired.
5. Rounding War: Using a deck of cards (take out the face cards and 10s), split the deck between two players. Each player turns over 2 cards (3 for 3-digit numbers or 4 for 4-digit numbers). Each player rounds his/her number to the nearest ten (or hundreds/thousands). Whoever has the greatest rounded number (or lowest) wins! Winner takes all the cards and the next hand resumes as usual. The player with the most cards at the end wins!
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