Video Lesson

Lesson Objective

Dear Learners,

At the end of this section, you should be able to:

• Identify measurement scales in their surrounding(multiple and fractions of the scales);
• State and use standard units of measures and their relationship with units in their surrounding.
• Discuss about the measures used in their local environment and comment on the practice;
• List standard units of measures and their relationship with units in their surroundings.

Brainstorming Question

What is a standard in measurement?

Key terms and concept

Scales

In physics scale is a set of numbers, amounts,… etc. used to measure or compare the level of something.

Here is a list of types of scales used in various fields, particularly in measurement and statistics, along with their definitions:

1. A nominal scale is a categorical scale used for labelling variables without any quantitative value.

Examples: Gender (male, female), blood type (A, B, AB, O), nationality (American, Canadian, Mexican).

2. An ordinal scale is used to order or rank items, but the intervals between the ranks are not necessarily equal.

  Examples: Education level (high school, bachelor’s, master’s, doctorate), satisfaction ratings (satisfied, neutral, dissatisfied).

 3. An interval scale measures variables with equal intervals between values, but there is no true zero point.

Examples: Temperature in Celsius or Fahrenheit, calendar years (2020, 2021).

4. A ratio scale has all the properties of an interval scale, but it also has a true zero point, which allows for the calculation of ratios.

Examples: Height, weight, age, income.

5. An absolute scale is used to measure quantities with a true zero and fixed units.

Examples: Length in meters, mass in kilograms, time in seconds.

Standards

In 2019, an International Committee revised a set of standards for length, mass, time and other basic quantities. The system established is an adaptation of the metric system and is called the SI system of units.

Standard units are conventional units which are used to measure physical quantity scientifically.

• Length: Meter is the standard or international system (SI) unit for length. There are also other non-SI units of length. These are centimeter(cm), millimeter(mm), and kilometer(km).
• Mass: The kilogram(kg) is the standard or international system (SI) unit of mass. The non-SI units of mass are gram(g), milligram(mg), and tone.
• Time: The unit of time in SI system is second(s). The non-SI units of time are minute (min), hour(hr), day, month and year.

Scientific notation

scientific notation is a way of writing measured values that are too large or too small to be conveniently written as a decimal. This can be written more easily in scientific notation ,in the general form: d×10ⁿ Example:

Decimal notation	Scientific notation
2	2×100
−53000	−5.3×104
0.00000000751	7.51×10−9

Significant Figure

Significant figures in a number are the digits that carry meaningful information about its precision. This includes all non-zero digits, any zeros between significant digits, and any trailing zeros in the decimal portion. Here are some examples to illustrate significant figures:

1. 123.45

• Significant Figures: 5
• Explanation: All the digits are non-zero, so they are all significant.

2. 0.00456

• Significant Figures: 3
• Explanation: The leading zeros are not significant. The digits 4, 5, and 6 are significant.