How are observations and measurements related?

Sometimes observations involve measurements.

A measurement is a description that includes a number or a unit.

Measurements Can Quantify Observations

Quantitative observations: observations that you make dealing with quantity, like a number or an amount.

Quantitative observations can be made with standardized instruments or approximations and comparisons.

Standardized Instruments:

Rulers**,** Meter sticks**,** Balances**,** Graduated cylinders

Approximations and Comparisons:

Larger, Shorter, Heavy

Qualitative observations:  observations you make about characteristics or qualities.

Color, Odor, feels like, sounds like

How are measurements expressed?

Numbers and units

A unit is a standard of measurement and vary depending on measurement system

Scientists most often use the International System of Units (SI).

By Using the International System of Units

Length and Area (meters) - Length: is a measurement of distance.

Area: is a measurement of how much surface something has.

Volume (liters): a measurement of the amount of space something occupies.

Volume = length x width x height

Volume of a solid is usually measured in cubic meters or cubic centimeters.

Volume of a liquid is usually measured in liters or milliliters.

One milliliter = one cubic centimeter.

Mass (grams): a measure of the amount of matter that makes up something.

Temperature (Celsius): a measure of how hot or cold something is.

By Using Scientific Notation

Is used to express large or small measurements.

Is a method of writing a quantity as a number multiplied by ten to the power.

What common measurements are made with scientific tools?

Graduated Cylinder – used to find volume

Triple beam balance or an electronic scale – used to find mass

Stop Watch – used to find how long it takes something to occur

Thermometer – used to find out how hot or cold something is

Compass, map, motion detector or GPS – used to measure position

Spring scale or scale – used to find out how much something weights

Ruler, meter stick, or GPS – used to find out length

Why is technology important to scientific measurement?

Makes it safer, easier, and more accurate.

Computers alone can store, calculate, and analyze data.

Computers can also make graphs, spreadsheets, can create models and simulations.

Technology Makes Difficult Measurements Possible

Probeware, microscopes, robots and satellites

Technology Improves Measurements and Saves Time

New developments improve old technologies and creates new ones that can take better measurements, are more portable and saves time.

How do scientists evaluate tools and measurements?

Selecting tools depends if the measurement needs to be exact or close enough.

By Considering Precision and Accuracy

Accuracy – compares a measured valued of a property with the standard value accepted for that property.

Precision – an exactness and repeat-ability of a measure.

With Estimates and Approximations

Approximations – a number value of limited accuracy.

Estimates – is a rough value representing an actual amount.