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Practice Experiment

Practice Experiment: Do this experiment together with your student/child. It will allow you to demonstrate all the necessary parts of the scientific method.

Materials:
• Small heavy object (marble, lug-nut, coin, rock)
• Tall, closable, container of a “thick liquid” (honey, shampoo, corn syrup)
• Stop watch (or some way to measure seconds)
• Bucket (or sink, or large bowl)
• Hot water, cold water + ice

SCIENTIFIC METHOD

STEP 1: Make an observation
Hot maple syrup pours faster than cold maple syrup.

STEP 2: Ask a question
What is the effect of temperature on viscosity (i.e., “thickness” of a fluid)?

STEP 3: State a hypothesis
This is a prediction that answers the question asked. There are 3 basic choices. Allow the student to pick the ONE they think is most logical:

Hypothesis 1: As temperature increases, viscosity increases (i.e., it becomes thicker)
Hypothesis 2: As temperature increases, viscosity decreases (i.e., it becomes less thick)
Hypothesis 3: As temperature increases, viscosity is not changed (i.e., no effect)

STEP 4: Conduct an experiment
So now you need an experiment that will change temperature (independent variable) and measure how viscosity (dependent variable) changes. The control (the results you compare changes to), are the room temperature trials because that is the “regular” temperature.

1. Put the marble (object) into the corn syrup (fluid) and close the container.
2. Flip the container and measure the time it takes for the object to fall through the fluid.
3. Repeat 5 times, record times on table (below)
4. Put container into bucket of hot water for 15 minutes, then repeat steps 2-3
5. Put container into bucket of ice water for 30 minutes, then repeat steps 2-3

STEP 5: Analyze results
Temperature: Colder/ Room Temperature/ Warmer
Trial #1__________#1__________#1___________
Trial #2__________#2__________#2___________
Trial #3__________#3__________#3___________
Trial #4__________#4__________#4___________
Trial #5__________#5__________#5___________

What is the average time for each category?
Colder (lower temperature) _____________________________________________
Room Temperature Control (“regular” temperature) _______________________
Warmer (higher temperature)_____________________________________________

STEP 6: Make a conclusion
Do the results support the hypothesis? In other words, as the temperature increased from cold to warm, did the viscosity increase (thicker fluid would mean longer times) or decrease (thinner fluid would mean shorter times) or did nothing happen (times all the same)?

Ultimately, the answer is yes if the average times changed in the same direction as the hypothesis predicted or no if the average times do not.

What could you do next?
Answer: Repeat with a different object, or a different fluid, or more temperatures.

What could you do better?Answer: Measure the temperatures of the fluid so that the independent variable is also quantitative.


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