• description

• explanation

• International System of Units (SI)

Measurement and Scientific Tools

• accuracy

• precision

• significant digits

Lesson 2-1• 1. A spoken or written summary of

observations is called a description.• a. An observation that uses the senses is

called a qualitative observation.• b. An observation that uses numbers is

called a quantitative observation.• 2. An interpretation of observations is

called an explanation.

A. Description and Explanation

Lesson 2-2• 1. The

internationally accepted system for measurement is theInternational System of Units (SI).

• 2. The seven base units are the meter, kilogram, second,ampere, Kelvin, mole, and candela.

The International System of Units

Lesson 2-2• 3. A description of how close a measurement is to an accepted value iscalled accuracy.

• 4. A description of how similar or close measurements are to each other iscalled precision.

Lesson 2-2The data taken by student A are more accurate because each value is close to the accepted value. The data taken by student C are more precise because the data are similar. ***THIS IS NOT ON YOUR NOTES***

Lesson 2-2The International System of Units (cont.)

How do accuracy and precision differ?

Lesson 2-3Measurement and Accuracy• 1. Tools used to measure quantities

can limit the accuracy of a measurement.

• 2. A thermometer with measurements divided into tenths is more accurate than a thermometer with measurements divided into whole numbers.

Lesson 2-4

• 1. When you take any measurement, some digits you know forcertain and some digits you estimate.

• 2. Significant digits are the number of digits in a measurement that areknown with a certain degree of reliability.

• 3. When you use significant digits, others can know howcertain your measurements are.

Significant Digits

Lesson 2-4

Lesson 2-4

Using significant digits lets others know how certain your measurements are.

Significant Digits (cont.)

Lesson 2-4Significant Digits (cont.)

Why should you use significant digits?

Lesson 2-51. A science journal is used to record descriptions, explanations,plans, and steps used in a scientific inquiry.

Scientific Tools

Corbis

Lesson 2-52. A(n) balance can be used to measure the mass of an object.

Scientific Tools (cont.)

The McGraw-Hill Companies, Inc./Stephen Frisch, photographer

Lesson 2-5•3. The temperature of substances is measured using a(n) therrmometer.•4. The kelvin is the SI unit for temperature, but in the scienceclassroom, temperature is measured in degrees Celsius.•5. Thermometers should not be used to stir anything.

Scientific Tools (cont.)

The McGraw-Hill Companies Inc./Ken Cavanagh Photographer

Lesson 2-56. Liquids are held, poured, heated, and measured inlaboratory glassware.

Scientific Tools (cont.)

Lesson 2-57. A(n) microscope is used to observe small objects that cannot be observed with an unaided eye.

Scientific Tools (cont.)

Photodisc/Getty Images

Lesson 2-5•8. Computers are used to compile, retrieve, and analyze data forreports; to create reports and other documents; to send information to others; and to research information.

•a. Hardware is made of the physical components of computers, such as monitors and keyboards.

•b. Software is the term used for programs that run on computers.

Scientific Tools (cont.)

Lesson 2-6

• 1. A handheld lens that magnifies, or enlarges, the image of theobjects observed through it is called a(n) magnifying lens.

• 2. To prepare objects or substances for observation under a compoundmicroscope, you would use a thin, rectangular piece of glass calleda(n) slide.

Tools Used by Life Scientists

Lesson 2-6• 3. Scalpels and

scissors are dissecting tools that are used toexamine tissues, organs, or prepared organisms.

• 4. A small glass or plastic tube similar to an eyedropper that is used to draw up liquidsand transfer them to another place is called a(n) pipette.

Tools Used by Life Scientists (cont.)

Photodisc Collection/Getty Images

Ingram Publishing/SuperStock

Lesson 2-6Tools Used by Life Scientists (cont.)

What are some tools used by life scientists?

Lesson 2 – LR1

A. accuracy

B. explanation

C. precision

D. significant digit

Which term refers to a description of how close a measurement is to an accepted or true value?

Lesson 2 – LR2

A. SI unit

B. significant digit

C. prefix

D. description

Which can be added to a base unit’s name to indicate either a fraction or a multiple of that base unit?

Lesson 2 – LR3

A. microscope

B. petri dish

C. thermometer

D. triple-beam balance

Which of these is used by scientists to measure mass?