aim 3: how do we use lab equipment to make observations and take measurements?

AIM 3: HOW DO WE USE LAB EQUIPMENT TO MAKE

OBSERVATIONS AND TAKE MEASUREMENTS?

DO NOW: ANSWER THE FOLLOWING QUESTIONS 1. What is the purpose of using laboratory tools and equipment? - Makes experiments more accurate and precise - Makes experimentation safer - Makes observations easier

DO NOW: ANSWER THE FOLLOWING QUESTIONS 2. Why is it important that we use these tools properly? - Ensures lab safety - Ensure that we have accurate and precise results - If we learn to use lab equipment correctly, scientists should be able to obtain the same results when they repeat the experiment

Devised by a group of French scientists to create a system of standard measurements (Centimeter, meter, kilogram, millimeter, milliliter etc)

Different from what we usually use (Inches, feet, pounds, gallon etc)

Why is it important that all countries use the metric

system?

METRIC SYSTEM HISTORY

Practice

I. LENGTH

a) What instrument is most commonly used to measure length?

_________________

b) What does cm stand for? ________________

c) How many reference marks make up one cm? ______

What are these reference marks called? ____________________

Therefore there are ____________________ in one centimeter

MILLIMETERS

10 MILLIMETERS

d) Answer the following questions:

d) Answer the following questions:

9

90mm/10 = 9 cm

II. VOLUMEa) What instrument is most commonly used to

measure volume? ______________________________

b) What unit should answers be expressed in?

________________ What is the abbreviation? _______

c) What is the curved surfacve of a liquid called?

______________________

GRADUATED CYLINDER

MILLILITERSmL

MENISCUS

d) What is the proper way to read a volume of a liquid?

___________________________________________

___________________________________________

*ALWAYS KEEP IT ON A FLAT SURFACE!

KEEP GRADUATED CYLINDER FLAT ON THE SURFACE AND

READ THE BOTTOM OF THE MENISCUS AT EYE LEVEL

e) Answer the following questions:

III. TEMPERATUREa) What instrument is most commonly used to

measure temperature? ______________________________


___________________ What is the abbreviation? _______

c) What other scale can temperature be expressed in?

_______________________________________

d) Why should you NOT hold the thermometer in your hand when taking a reading?

e) Similarly, when taking a temperature reading of a liquid, why should the thermometer not touch either sides or bottom of the container?

We want the temperature of the water not the beaker. This could change our observations and results

Our hand can transfer heat/cold to the thermometer which will not give us a true reading of the liquid

f) Read the following temperature scales and report your answers to the nearest tenth of a degree.

13 98.3 - .7

IV. MASS

a) What instrument is most commonly used to measure mass? ______________________________


___________________ What is the abbreviation? _______

c) Calculate the mass for each triple beam balance below

Mass: 37.3 g

c) Calculate the mass for each triple beam balance below

Mass: 536.8 g

V. WHAT IS THE DIFFERENCE BETWEEN ACCURACY AND PRECISION? 1. Accuracy:

2. Precision:

How close a measurement is to the real value/accepted value (proper equipment)

How close a series of measurements are to one another (good technique)

V. HOW COME ALL MEASUREMENTS HAVE SOME LEVEL OF INACCURACY AND UNCERTAINTY?

There will always be errors due to the experimenter, the equipment and changes in experimental conditions.

*This is why it is important that we repeat measurements and experiments MORE THAN ONCE!

VI. HOW DO LABORATORY TOOLS IMPROVE THE OBSERVATIONS MADE BY A SCIENTIST?

It increases the accuracy, makes observations easier and allows experiments to be easily repeated.

aim 3: how do we use lab equipment to make observations and take measurements?

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