Review 2Collecting Data

Observing

Observing is collecting information by using your senses or measuring.

Microscopes magnify objects by making them appear larger then they are. Microscopes allow scientists to see very

small details They can look at blood and tissues to see

harmful bacteria and viruses

Observing

Hand lenses are used by scientists to see finer details of objects. They are good for viewing details and

small parts of objects like a flower.

Telescopes are the most powerful magnifiers. They all scientists to see objects in outer space.

Hubble Telescope

Hubble is a telescope that orbits Earth. Its position above the Earth gives it a view of

the universe that is much better than the telescopes on the ground.

It has beamed hundreds of thousands of images of space back to Earth.

Click here to see where Hubble is now.

Observing

These two pictures are of the same flower. The one on the right is magnified with a hand lens.

What can you see in the right flower that you cannot see in the left?Why is it important to use hand lenses, microscopes, and telescopes rather than just our eyes to observe objects?

Measuring

Scientists need accurate measurements so they can correctly interpret their data.

Scientists use measuring instruments such as metersticks, balances and stopwatches.

There are errors in every measurement, so scientists take multiple measurements to check their results.

Measuring

Heather wants to measure how long it takes her father to drive from Pittsburgh to Harrisburg.

How can she measure this?

Can you think of any ways in which an error could be made in this measurement?

Measuring

An estimate is an approximate measurement obtained without actually counting or measuring something. There are about 300 students at East

Elementary. The doorway is about 2 meters high

Estimate the number of fourth graders there are at East Elementary.

Measuring Instruments

Scientists use different instruments to collect data.

Balance• Used to measure mass (weight)• Grams, kilograms, milligrams

Graduated Cylinder• Used to measure an amount of liquid• milliliters (mL), Liters (L)

Measuring Instruments

Thermometer• Used to measure temperature – how hot or cold• Degrees Celsius• Measure weather, bath water

Ruler or Meterstick• Used to measure length• Rulers: centimeters, millimeters•Metersticks: meters, decimeters

Measuring Instruments

Which of these instruments would you use?

Stopwatch Meterstick BalanceGraduated cylinder Ruler

To measure: Your desk The speed of a kid on a skateboard Mass of your Science workbook The amount of rain that fell last night A dry erase marker

Measuring

Metric system is the most common system for making measurements. Units: meter for length, kilogram for weight/mass,

liter for volume, degrees Celsius for temperature

U.S. customary system is used by many people in the U.S. (but not usually scientists). Units: inches and feet for length, ounces and

pounds for weight, gallons for volume, degrees Fahrenheit for temperature