Introduction
When making observations, scientists usually make objective quantitative measurements rather than subjective qualitative judgments. Such quantitative measurements are preferred because they minimize observer bias. However, even objective quantitative measurements may be subject to bias if taken incorrectly. Furthermore, even the best measuring tools are imperfect and possess errors. Thus it is important to know the proper use of measuring devices and to understand the limitations of a particular device.
In this laboratory exercise, you will learn how to collect data using different measuring devices. You will learn about the metric system and how to present data in the form of data tables and how to calculate averages and standard deviations to summarize your seed pod data. In addition, you will learn how to graph data to summarize data trends and illustrate relationships.
The Metric System
In the United States we still rely heavily upon the US system for measurement. For example, we still measure distance in inches, feet, yards and miles. We measure mass in ounces, pounds and tons. We measure volumes in ounces, pints, quarts and gallons.
This system is cumbersome, especially when we need to measure in fractional units. For example, half a foot equals six inches. In order to convert distance measured in feet to distance measured in inches, we need to remember that there are 12 inches to the foot. In order to convert yards to feet, we need to remember that there are 3 feet to the yard. In order to convert miles to yards, we need to remember that there are 1760 yards to the mile.
The metric system is based upon multiples of ten and fractional values are presented as decimals. Thus there are 1000 millimeters, 100 centimeters, or 10 decimeters in one meter (one meter is a little longer than a yard). In addition, 10 meters equals 1 decameter, 100 meters equals 1 hectometer, and 1000 meters equals 1 kilometer. From these...