CHAPTER 0 LESSON 2 MEASUREMENT & TOOLS

A1. DESCRIPTION & EXPLANATION A spoken or written summary of observations is known as a description.

A1a. DESCRIPTION & EXPLANATION A qualitative description is one in which the senses are used to describe an observation.

A1b. DESCRIPTION & EXPLANATION A quantitative description is one in which numbers and measurements are used to describe an observation.

A1c. DESCRIPTION & EXPLANATION An interpretation of observations is called an explanation.

A2. DESCRIPTION & EXPLANATION The internationally accepted system for measurement is called the International System of Units, which is abbreviated as SI.

A3. DESCRIPTION & EXPLANATION The SI system of measurement has standards of measurement called base units and a set of prefixes to tell the size of the unit.

A4. DESCRIPTION & EXPLANATION It is easy to convert from one SI unit to another because SI is based on units of ten.

A5. DESCRIPTION & EXPLANATION There is uncertainty in any measurement because determining exact measurements with certainty can be problematic.

A5. DESCRIPTION & EXPLANATION Therefore, a measurement always involves some amount of guessing.

A6. DESCRIPTION & EXPLANATION The number of digits in a measurement that you know with a certain degree of reliability are called significant digits.

A6a. DESCRIPTION & EXPLANATION To achieve the same degree of precision as a previous measurement, it often is necessary to round a number.

A6b. DESCRIPTION & EXPLANATION If the digit to the right of the digit being rounded is less than 5, the digit being rounded stays the same

A6b. DESCRIPTION & EXPLANATION if the digit to the right of the digit being rounded is 5 or higher, the digit being rounded is increased by one.

A7. DESCRIPTION & EXPLANATION There are four values often used when scientists analyze numbers in their data.

A7a. DESCRIPTION & EXPLANATION When the data in a data set are arranged in numerical order, the middle number in the list is the median.

A7b. DESCRIPTION & EXPLANATION The mode of a data set is the number or item that appears most often.

A7c. DESCRIPTION & EXPLANATION The mean of a data set is the sum of the numbers in the set divided by the number of entries in the set.

A7d. DESCRIPTION & EXPLANATION The range is the difference between the greatest number and the least number in the data set.

B1. SCIENCE TOOLS A notebook that you use to take notes or record information and data while you conduct a scientific investigation is called a science journal.

B2. SCIENCE TOOLS Making measurements of lengths and distances is commonly done with rulers and metersticks, using base units of meters.

B3. SCIENCE TOOLS To measure the volume of a liquid, use a graduated cylinder and units of liters or milliliters.

B4. SCIENCE TOOLS To measure the mass of an object, use a triple-beam balance and units of grams or kilograms.

B5. SCIENCE TOOLS To measure the temperature of a substance, use a thermometer and units of degrees Celsius.

B6. SCIENCE TOOLS Computers are useful for collecting, organizing, storing, analyzing data, and ultimately sharing results worldwide over the Internet.

C1. EARTH SCIENCE TOOLS Earth scientists use binoculars to get a clearer look at distant or faraway objects, including landforms, animals, and weather.

C2. EARTH SCIENCE TOOLS Earth scientists use a compass to navigate and to determine the direction of objects.

C3. EARTH SCIENCE TOOLS Wind direction is measured by a wind vane; wind speed is measured by an anenometer.

C4. EARTH SCIENCE TOOLS To help identify minerals, people use a piece of unglazed porcelain called a streak plate; the color of the mark left is called the mineral’s streak.