Using A Round-O-Meter To Estimate
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Kathleen M.K. Pidrak Edward H. White
1137 W. 122 St.
Chicago IL 60643
The student will demonstrate knowledge of rounding numbers to the nearest
dollar or nearest dime.
scissors string tape pencil
Round-O-Meter worksheet Round It Game overhead
Overhead School Store paper base ten blocks
graph for base ten blocks
1. Introduce several items that students would need to purchase for school.
Write the items and their cost on the board. Talk about how we need to round to
get an idea of how much money we need.
2. Using paper copies of the base ten blocks on a graph show if a number
falls above or below the half mark. If we are closer to the first number we
round down, if we are closer to the second number we round up. For our lesson
we will let 1 flat represent a dollar, one rod represent a dime and one unit
represent a penny. Demonstrate several of the items that the students
mentioned. Pass out individual pieces of the base ten papers and a graph so the
students can try this for themselves.
3. A Round-O-Meter is an instrument that we will make to show us which
direction to round. The Round-O-Meter is a piece of paper about the size of a
ruler. Attach a piece of string to the center of the Round-O-Meter, one end is
folded into an arrow. Write the numbers 1, 2, 3, 4, 0 on the end of the strip
with the arrow. Write the numbers 5, 6, 7, 8, 9, on the other end of the paper.
When you hold the Round-O-Meter by the string and put a paper clip on the number
you are looking at, the arrow will go up or down. This will show the children
which direction to round.
4. After the children use their Round-O-Meter several times to prove to
themselves that it will work there is a follow up worksheet that they can use to
reinforce their new skill.
Showing the children that one number is closer to another is very
beneficial in that they can easily figure which direction to round. The Round-
O-Meter serves as a reminder and is something that they can keep at their desk.