1. OOPS! My Bad!
By: Ella W.

2. I Will Be Using:
A Quarter
A Half Dollar
Eisenhower Dollar Coin

3. My Diameter Measurements:
Quarter: 22 millimeters
Half Dollar: 29 millimeters
Eisenhower Dollar Coin: 37 millimeters
Quarter: mm
Half Dollar: mm
Eisenhower Dollar Coin: mm
My Diameter Measurements:
Actual Diameter Measurements:

4. Percent of Error:
How to Find Percent of Error (example)
Prediction: 2 cookies Actual Amount: 3 cookies
Step 1: divide your prediction by the
actual number.
2 ÷ 3 =
Step 2: Multiply that quotient by 100. (or move
the decimal two places to the right)
x 100 =
Step 3: Subtract that product from 100.
100 – = % of error
of cookie prediction.

5. Using the Percent Error formula, I found the percentage errors of my measurements.
Quarter Percent of Error: %
Half Dollar Percent of Error: %
Eisenhower Dollar Coin: %

6. Observations
It is not quite as easy as I thought to find an exact measurement.
It makes it easier to do a problem if you write out the instructions first.
When measuring something small, make sure the starting point of the ruler is right on the edge of the object.

7. Thank you for Watching!