1. Measurements and the Scientific Method
Chemistry
Objectives 1: a,b and 3

2. Essential Questions What is a measurement? Why do we use units?
How do you make a proper measurement?
What is the scientific method and how does it work?

3. Science and Chemistry What is science?
The study of the world around us
What is chemistry?
The study of the composition of matter and the changes that matter undergoes.
Matter is anything that has mass and occupies space.

4. Measurement What is a measurement?
A measurement is a quantity that has both a number and a unit.
How are measurements used in science?
To collect data and to keep track of the amounts being used

5. Units What is a unit? Units are standard values Why do we use units?
Units allow people to be able to compare data and to be consistent

6. Types of Measurements
Qualitative measurements deal with observations or “qualities”.
Quantitative measurements deal with numbers or “quantities”.

7. Types of Measurements
Label the following as quantitative or qualitative
A wooden block is 1 foot in length
A wooden block is red in color
The solution is blue
The solution is 321 mL in volume
quant
qual
qual
quant

8. Measurement
Every experimental measurement has a degree of uncertainty.
The volume, V, at right is certain in the 10’s place, 10mL<V<20mL
The 1’s digit is also certain, 17mL<V<18mL
A best guess is needed for the tenths place.

9. Measurement (cont)
Three differently calibrated meter sticks are used to measure the length of a board. a) A meter stick calibrated in a 1-m interval. b) A meter stick calibrated in 0.1-m intervals. c) A meter stick calibrated in 0.01-m intervals. Measuring How many significant figures are reported in each measurement?

10. Measurement (cont) What is the Length?
We can see the markings between cm
We can’t see the markings between the .6-.7
We must guess between .6 & .7
We record 1.67 cm as our measurement
The last digit 7 was an estimate but all three numbers are still part of the measurement

11. Learning Check What is the length of the wooden stick? 1) 4.5 cm

12. Lab Equipment Match the following to the proper measuring tool
Temperature
Mass
Density
Volume
Graduated cylinder
Scale/balance
Scale/balance and ruler
Thermometer
Answer Key: 1 = D, 2 = B, 3 = C, 4 = A

13. The Scientific Method What is the scientific method?
The scientific method is a logical, systematic approach to the solution of a scientific problem.

14. The Scientific Method
What steps are involved in the scientific method?
Making observations and collecting data
Writing hypotheses and/or purpose
Conducting the experiment
Analyzing the results of the experiments

15. Observations and Data What is an observation? What is data?
When you use your senses to obtain information
What is data?
Information collected during an experiment

16. Hypotheses/Purpose
Hypothesis is a prediction (an educated guess) or a proposed explanation for an observation
Purpose is the goal of the experiment

17. Conducting an Experiment
Experiment is the process of testing a hypothesis or meeting a purpose
Variables are factors that may change during an experiment
Several trials should be conducted with only one variable being changed through all of the trials

18. Variables Independent variable is the variable being changed
There should only be one independent variable being changed during an experiment
Dependent variable is a variable that changes in response to the change in the independent variable

19. Analyzing Results How do you analyze results?
You look for patterns in your results
You compare back to your hypothesis/purpose
Did you meet your purpose?
Was your hypothesis correct?

20. Science and the Scientific Method (cont)
The steps in the scientific method do not have to occur in the order shown. Comparing and Contrasting How are a hypothesis and a theory similar? How are they different?
Theory explains observations or phenomenon
Scientific law describes a set of observations or phenomenon

21. Design an Experiment
Lemon trees receiving the most water produce the largest lemons.
Write a hypothesis/claim.
Identify the independent variable:
Identify the dependent variable:
List 2 possible constants:
Explain what you might use for a control.

22. Design an Experiment (cont)
The temperature of water is measured at different depths in a lake
Write a hypothesis/claim.
Identify the independent variable:
Identify the dependent variable:
List 2 possible constants:

23. Essential Questions What is a measurement? Why do we use units?
How do you make a proper measurement?
What is the scientific method and how does it work?

24. Measurements and the Scientific Method Assignment
Worksheet