Scientific Method

A logical method of problem solving

Steps of the Scientific Method

1. Making observations that lead to a question.

2. Forming a hypothesis to answer the question.

3. Testing the hypothesis by experimentation.

4. Making a conclusion based on the results of the experiment.

Definitions:

• Observing: Use of the senses and devices in the lab to obtain information.

• Conclusion: A statement based on observations and prior knowledge.

Label each of the following as an Observation or Conclusions

1. The milk tastes sour.

2. The sour milk must be spoiled.

3. The temperature of liquid is 33oC.

4. The wire must be made of copper because of its color.

5. It must be about to rain because the sky is getting dark.

6. When powder is added to water, it fizzes.

7. The gas blown on the candle must be CO2 because the flame went out.

8. Lemon juice is an acid and tastes sour. All acids must taste sour.

Check Your Answers

1. The milk tastes sour.O

2. The sour milk must be spoiled.C

3. The temperature of liquid is 33oC.O

4. The wire must be made of copper because of its color.C

5. It must be about to rain because the sky is getting dark.C

6. When powder is added to water, it fizzes. O

7. The gas blown on the candle must be CO2 because the flame went out.C

8. Lemon juice is an acid and taste sour. All acids must taste sour.C

Step 1: Observations

• 1. Quantitative: Includes numbers and units. Ex. 100oC

• 2. Qualitative: Does not include numbers and units. Ex. Hot

Scientific Method Candle Lab• Get in a group of 4 people and title one sheet

of notebook paper as above. Put all group members names on the top of the paper

• Supplies: Each group will need a candle, ruler, matches, and balance

Scientific Method Candle Lab• Write down the word Observations: and

number 1-8.• Using complete sentences, make 8

observations before, during, and after lighting a candle. Allow the candle to burn for 5 minutes. Be sure to include quantitative and qualitative observations.

• Using your observations, draw a conclusion.

Circle any of the observations that match yours and label as Qual(L) or

Quantit(N) observations on notes1. The candle is white.

2. The candle is shaped like a cylinder.

3. This candle has a diameter of 2.1 cm.

4. The candle’s material smells like wax.

5. The candle material is soft enough to be scratched.

6. The candle is lit by holding a flame close to the wick.

7. The flame is about 2 cm tall and 1 cm wide.

8. After the flame goes out, the liquid solidifies after 5 seconds.

Check your answersL=Qualitative

N=Quantitative1. The candle is white. L

2. The candle is shaped like a cylinder. L

3. This candle has a diameter of 2.1 cm. N

4. The candle’s material smells like wax. L

5. The candle material is soft enough to be scratched. L

6. The candle is lit by holding a flame close to the wick. L

7. The flame is about 2 cm tall and 1 cm wide. N

8. After the flame goes out, the liquid solidifies after 5 seconds. N

Step 2: Hypothesis: an educated guess

A good hypothesis:

1. Explains an observation.

2. can be tested

3. will predict an outcome

Scientific Method Candle Lab

Write down the word Hypothesis: on your lab sheet

Form a hypothesis for each question:

1. What is the purpose of the candle’s wax?

2. As the candle burns it gets shorter. Where does the wax go?

Step 3: Experiment:

1. is designed to test a hypothesis.

2. involves variables

3. is performed under controlled conditions

Variables: factors that can be changed.

Control: a variable that is held constant

In a good experiment:

a. only two variables are allowed to change.

b. the manipulated(or independent) variable is changed by the scientist.

c. the responding (or dependent) variables changes as a result of the experiment.

d. all other variables are controls because they are held constant.

Step 4: Conclusion:

• the final step of the scientific method made from the results of an experiment.

Scientific Method Candle LabWrite down the words Experiment and

Conclusion: on your lab sheet

Test the hypothesis you formulated for the purpose of the candle’s wax.

1. Obtain a piece of cotton string to simulate the wick. Holding the wick with a forcep, light the string and observe.

2. Was your hypothesis correct? Formulate a conclusion based on your observation about the purpose of the candle wax.

Scientific Method Candle Lab

Test the hypothesis you formulated for where the wax goes as the candle burns.

1. Record the mass before and after burning a candle for 5 minutes or find a group that recorded mass as an original observation.

2. Was your hypothesis correct? Formulate a conclusion based on your observation about what happens to the wax.