a straightedge
I believe they are called graduations
It is known as a semi-circular protractor.
Ruler
A ruler can be classed as a straight edge.
a bit of plastic
a straightedge
The marks on a ruler are called increments or graduations. These marks help with measuring and assessing lengths accurately.
The answer depends on the graduation (markings) on the ruler.
a flat wooden stick
You look at the markings on its edge.
It is between 1.3 and 1.4: nearer to 1.4. It is 1 3/8 if your ruler has markings in eighths.
On a 30cm ruler you can't get it exactly, you need a higher tech ruler which has the markings of 2.54cm. If you have a normal ruler you have to estimate.
A precision unit of a ruler typically refers to the smallest increment of measurement marked on the ruler. For example, a ruler with millimeter markings has a precision unit of 1 millimeter.
That depend on how long the ruler is. The 2 rulers in my desk drawer have 200 and 300 milimeters markings respectively. I also have a triangle with 195 millimeter markings on one side. I just looked in another drawer and found a ruler with 400 mm markinga and a folding carpenter's rule with 2000 markings.
To measure in millimeters (mm), use a ruler or measuring tape with markings in millimeters. To measure in centimeters (cm), use a ruler or measuring tape with centimeter markings. For meters (m), use a meter stick or measuring tape with markings in meters. Simply align the start point of the object you are measuring with the zero mark on the ruler or tape and read the measurement at the endpoint.
The distance between the 0 and 1 markings on a metric ruler.