If you are trying to teach your child how to read and to measure with a ruler, you might find it difficult to measure to the tenths of an inch. This is because a standard English ruler, most commonly used in the United States, is measured in sixteenths and eighths of an inch. You can convert your measurements to tenths of inches by using a converted decimal ruler.

Place your decimal ruler on a flat surface where you can clearly read it. Reading from left to right, your decimal ruler, like the standard ruler, has the numbers 1 through 12, which represent the inch marks.

Note the nine vertical dashes labelled 1 through 9 between the inch marks. They represent 1/10 inch or 100/1000 inch (one hundred thousandths of an inch).

Measure an object and convert your measurement to tenths of an inch. For example, measure a standard, sharpened pencil. If your measurement comes out to 5 inches and 4 vertical dashes, then your pencil is 5 and 400/1000 inches. This reduces to 5.4 inches.

Count the vertical dashes between each of the 1 through 9 numerals. There are nine. Each represents 0.10. Therefore, if you measure an object that is 5 solid inches, but it also stretches a little farther to the eighth dash past the 200/1000-inch mark, then you would need to add 5.0 + 200/1000 (or .200) + 800/1000 (or .80) for a total of 5.28 inches.