What is measurement?
Measurement is the process of quantifying the properties of an object by expressing them in terms of a standard unit. Measurements are made to answer such questions as, How heavy is my parcel? How tall is my daughter? How much chlorine is in this water?
How do we measure?
The process of measuring consists of three main steps. First, you need to select an attribute of the thing you wish to measure. Second, you need to choose an appropriate unit of measurement for that attribute. Third, you need to determine the number of units.
What procedures are used to determine the number of units?
Some measurements require only simple procedures and little equipment -- measuring the length of a table with a meter stick, for example. Others -- for example, scientific measurements -- can require elaborate equipment and complicated techniques.
Is it possible to measure objects without using standard units?
Yes. Nonstandard units (i.e., units that are not agreed upon by large numbers of people) can be used to make comparisons and order objects. But because the units are nonstandard, there is limited value in using them to convey information.
How precise are measurements?
Measurement, by its very nature, is approximate. The precision of the measuring device tells us how finely a particular measurement was made. Measurements made using small units, such as square millimeters, are more precise than measurements made using larger units, such as square centimeters. The accuracy of a measure is determined by how correctly a measurement has been made. Accuracy can be affected by the person making the measurement and/or by the measurement tool. Precision and accuracy, and how to determine them, will be covered in later sessions.
Okay, then -- how large is my rock?
It all depends on how you define the word large. Your answer will be based on the attributes you decide to consider, such as weight, volume, surface area, and height.