Milk Lab and Experimental Design
Fill a petri dish with enough water to just cover the entire petri dish. Add two
different colors of food coloring (1 drop each) to the water at opposite ends of
the petri dish. Come up with a way to quantitatively measure what is
happening.
1. Record your observations when putting food coloring into the water.
2. Quantitative measurement: ___________________
3. What chemical property of water causes this to occur? Draw a molecular level
diagram of is occurring.
4. Predict what will happen when you put food coloring into milk.
Record your observations
5. What property of milk might account for the differences in observations between
the water and the milk trial?
Replace the milk and add the food coloring again. Now dip the end of a
toothpick into dish soap and touch the soap end to surface of the milk in the
middle of the petri dish.
6. Record your observations.
7. Now you are going to design your own experiment using the following procedure.
What scientific question are you addressing? This question should lead you to a
TESTABLE hypothesis
Question:
What is your hypothesis?
IV = independent variable
DV = dependent variable
IF (IV) ______________________________ and (DV) ____________________________ are related,
THEN when the (IV) __________________________ is (increased/decreased or describe
how you will manipulate the IV) then the (DV) _________________________________ will
(increase/decrease or describe how the DV will respond).
Procedure: Provide a DETAILED, STEP-BY-STEP procedure for your experiment
below. Be sure it is very specific so someone else would be able to repeat the
experiment if they wanted to. (You can do this as a list of steps.)
Materials: List all of the materials that you will need for this experiment. (A
bulleted list is okay here).
CHECK LIST
 How many VARIABLES does your experiment have?

What is your INDEPENDENT VARIABLE?

What is your DEPENDENT VARIABLE and how will you MEASURE it?

Do you have a CONTROL group? What does it lack?

How will you collect your data?

Is your data QUANTITATIVE or QUALITATIVE or are both present?

What are the CONSTANTS in your experimental set up?
Experimental Results / Data
 How will you collect and organize the results from your experiment?
 Think about the type of data you are collecting
 Create data tables on a separate sheet of paper.
 Make sure your tables are labeled so the reader knows what they are looking
at.
Graphs & Visual Aids:
 Graphs and/or visual aids (like a diagram or qualitative drawing) can be very
helpful when appropriate.
 Properly label all graphs and diagrams
Conclusion:
 Once the data has been visually represented in a meaningful way, it is time to
revisit the original question(s) that started this whole process of inquiry to
begin with and draw some conclusions.
 This is the MOST IMPORTANT part of the entire experiment because it is
where we find answers to our questions and develop new questions for
further investigation.
A GOOD CONCLUSION WILL
1. Revisit the hypothesis: Restate your original hypothesis, discuss the results of
the experiment and determine if the hypothesis was SUPPORTED or REJECTED by
the experimental results. Remember, a rejected hypothesis is just as valuable as one
that was supported. You should use actual data to support this claim!
2. Explain the Results: Regardless of whether your hypothesis was supported or
rejected, you will want to explain why things happened the way they did. This part
of your conclusion will require you to do some RESEARCH. Consult outside EXPERT
sources to find explanations what happened. This is probably the longest part of
your conclusion.
3. Critique the Experiment & Develop New Questions: No experiment is perfect
and there is always room for improvement. If you were to conduct the experiment
again, what would you change? What were the sources of experimental error? How
would you limit that error? Experimentation starts with a question and inevitably
leads to new answers. What questions have arisen from your results?