AP Biology (and all that fun stuff) by Kelly N.: The Scientific Method of Approach

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Kelly N. - Period 04 - AP Biology - September 1, 2014

The Scientific Method of Approach

How to correctly design and conduct an experiment.

The key components to designing an experiment are first having a problem and posing a question, then creating a hypothesis and designing an experiment. Herein you must have specific independent and dependent variables as well as the ever so closely monitored constants. After, you would design a procedure, materials list and conduct your experiment. Then you can record data and observations on a chart, diagram or table of some sorts, if that would suit your experimental needs best. Lastly, you would need a conclusion. Another thing to consider is if the experiment doesn’t work or goes wrong, you may have to redo and/or revise your entire experiment; multiple times, even.

Step 01:

The first thing you should do before anything in an experiment is to pose a question. A good question would be specific and easily understood, like for example “Do slow release fertilizers make tomato plants grow better than composted manure?“ Then you would construct that question into an if-then statement known as a hypothesis. “If 5 tomato seedlings were grown in five pots with a balanced combination of manure and soil, then they will grow taller than the 5 plants grown with chemical fertilizers and soil.” Depending on your educated guess and personal thoughts, you could move the parts after “if” and “then” however you please.

Step 02: Experimental Design

Your next step would be to design an experiment. When designing an experiment, there are several things you must consider. Factors like how long you want it to be, how many trials you will take, how often you take them, what your controls will be and how to maintain them so they don’t affect the experiment, etcetera. In the case of this experiment, the experiment would be to see whether chemical or natural fertilizers would make a number of tomato plants grow taller.

Independent variable: Slow-release fertilizer

Dependent Variable: Heights of plants

Control: Plants w/out fertilizer, but with manure

Constant(s): water intake, sunlight, temperature, and size of pots

Step 03: Materials

You will need:

· 10 – 5 gallon buckets
· 10 – started organic seedlings
· 3.75 cubic feet of potting soil
· 1.25 cubic feet of composted Black Cow brand manure
· 4 cup measuring cup
· Drill and ½” diameter pre-drill bit
· Miracle Gro slow release Shake ‘n Feed
· 1 tbsp measuring spoon

Step 04: Procedure

First, you will gather all materials needed. Then you will drill five holes, one in the middle and four equally apart around it, for drainage. Then you will empty .5 cubic feet of the generic potting soil into each of five buckets. Afterwards, you would fill the remaining five with .25 cubic feet of generic potting soil, and mix in .25 cubic feet of the Black Cow manure. Afterwards, you would plant one organic tomato seedling per bucket and line up all ten buckets in an area where they will receive equal sunlight (can be indoors or outdoors). Finally, you would sprinkle 2 tablespoons of Miracle Gro Shake ‘n Feed slow release plant fertilizer into the pots with only potting soil. Record heights. Repeat recordings every 7 days for 28 days.

Step 05: Record Data

When measuring, record the heights of each plant in its respective place.

Plant Heights (in inches, per day)

Plants	Day 1	Day 7	Day 14	Day 21	Day 28
Plant 1
Plant 2
Plant 3
Plant 4
Plant 5
Plant 1
Plant 2
Plant 3
Plant 4
Plant 5