Experiment: Should I use fertilizer?
Carlos has a great idea. He thinks he might be able to earn extra money by selling zinnia flowers at school on Valentine's Day. Before he starts growing flowers, he needs to make a business plan to be sure that he will make money, not waste it.
Carlos goes to Home Depot and picks up a packet of zinnia seeds so that he can experiment. His hope is to eventually develop a method of growing these flowers indoors so he can make money. Carlos took Earth & Environmental Science, so he knows that dirt is dead. He needs good soil and perhaps some fertilizer to help his flowers grow fast and reliably. Carlos develops a hypothesis that states, "If I use fertilizer, then my plants will grow fuller, lusher, and produce more flowers."
Carlos grows two identical zinnia flowers in two separate paper cups. Once they are old enough, he transfers both flowers, identical in size and health, to two identical flower pots. He adds the same amount of soil and to each pot and puts both of his plants on the window sill where they can bathe in sunlight together. He plans to provide each plant with the same amount of water and will water them on the same schedule. He labels one, "Plant A" and the other, "Plant B."
Next, Carlos starts his experiment by beginning to test his hypothesis. He must add his independent variable, the fertilizer only to one zinnia plant. He chooses to add the fertilizer to Plant A.
To figure out whether adding fertilizer was a worthwhile investment, Carlos needs to collect data. So, once a month for 3 months, Carlos measures the growth of Plant A and Plant B. He can easily observe that the fertilizer is helping, but he still needs to analyze his data to prove it. Based on his measurements, it becomes clear that Plant A is significantly healthier and has produced more flowers than Plant B. Did Carlos prove his hypothesis was correct?
Parts of this experiment:
- Variables (things we could test) - plants, fertilizer, flower pots, soil, sunlight, temperature, water, time, plant health
- Control variables (things that stay the same) - plants, flower pots, type of soil, amount of soil, source of water, amount of sunlight, watering schedule
- Independent variable (thing we are testing) - fertilizer
- Dependent variable (outcome we are measuring) - plant size and number of flowers
- Hypothesis (if>then statement) - If I use fertilizer, then my plants will grow fuller, lusher, and produce more flowers.