ATI TEAS 7: Scientific Measurements & Tools Key Concepts

Measurement

A number plus a unit

Accuracy

How close a measurement is to the true value

Precision

How close repeated measurements are to each other

Accuracy vs Precision

Accurate = correct; Precise = consistent

SI System

Standard metric system used in science

Length (SI unit)

Meter (m)

Mass (SI unit)

Gram (g)

Volume (SI unit)

Liter (L)

Temperature (SI unit)

Degrees Celsius (°C)

kilo-

1,000

centi-

1/100

milli-

1/1,000

Metric conversion tip

Move the decimal left or right

Tool to measure length

Ruler or meter stick

Tool to measure mass

Balance or scale

Tool to measure liquid volume

Graduated cylinder

Tool to measure temperature

Thermometer

Tool to measure time

Stopwatch

Tool used to view small objects

Microscope

Tool used to transfer small liquid volumes

Pipette

Meniscus

Curved surface of a liquid in a container

How to read a meniscus

Read at the bottom of the curve

Independent variable

Variable that is changed (x-axis)

Dependent variable

Variable that is measured (y-axis)

Low microscope power

Larger field of view

High microscope power

Smaller field of view, more detail

Common measurement mistake

Reading the top of the meniscus

Mass vs Weight

Mass = amount of matter; Weight = force of gravity