How to Teach Fractions & Measurement Skills with a Ruler and an Inch
Through all of the math I have taught I frequently see that books teach basic ruler skills to the 1/2, 1/4, & possibly 1/8 in grades 1 & 2. In the 3rd & 4th grade books it is already an assumed skill, somewhere along the line the kids are just supposed to know that the normal inch ruler is divided into 16ths. This is all before students truly understand what a fraction is and what is the world is a 16th. Third and fourth graders naturally know what an 8th or a 4th is because they divide pies, pizzas, and other dividable items into those natural fractions. When looking at the standardized test that expects the students to know how to measure to the nearest 16th when they don't even know the comprehension of a fraction creates another entire problem.
In order to help my students truly understand how to read a ruler or measuring tape (which in an essential skill) i have laid out a few simple process to see how they work together to create the basics of an inch and how the fractions divide that inch into pieces.This skill is as much about understanding measurement as it is about understanding fractions, without one it is hard to wrap your head around the entire concept.
First I start with a measurement of 1 inch. Each student can do this on a piece of paper. One inch equals one whole part. I am going to create several pictures on one page so that my students can use it as a visual reminder of how the ruler and fractions are divided.
The second image I am going to create is halves. I am going to divide this one into two parts and I am going to signify the different parts with a color. I am going to use the color to signify the different parts of a fraction and eventually in our final image you will see how the color helps us recognize how the parts relate to each other.
From there we do the same image with fourths, eighths, and sixteens each one depicting an inch divided evenly into those fractions, each using a different color.
An Inch divided into sixteenths
An Inch Divided into Pieces
The last image is going to combine all of these concepts. Draw the inch and make them stating with the largest fractions first and working your way to the sixteenths. When writing a common name for a number write it directly below the previous name. Note that the first name of the number is the simplest form while the other s are equivalent fractions
Another great way to present this is do do them seperaly on an overhead transperancy and then stack the images.
For younger students I take a ruler and enlarge it on the copy machine onto cardstock so they can do the same project at a larger scale. This allows for understanding of the concept of how it is divided when their fine motor skills may have trouble writing in the small context of an inch.