Controlled Variables- temperature

Controlled Variables- temperature, humidity, container, soil
1. Plants need light to grow. Learn more about photosynthesis and chlorophyll
What effect does the amount of light have on the growth of a plant?
Note that the question identifies two variables: amount of light and growth of a plant.
Note that both variables are changed. You control the change in the amount of light and
you will be observing how the change in light affects the growth of a plant.
Note that both variables are measurable.
Cause-Independent Variable: amount of light
Effect- Dependent Variable: growth of plant
2. Plants have stems that grow upward and roots that grow downward. Learn more about geotropism.
What effect does the angle of growing medium have on the direction of plant stem and root growth?
3. Plants have green leaves because of the presence of chlorophyll. Learn more about chlorophyll and other plant pigments.
What effect does the amount of chlorophyll production have on the color of leaves?
Following are more examples of variables.
A variable is part of an experiment that can change, such as the amount of light, temperature, humidity, or plant growth as well as the direction of plant growth.
In an experiment, an independent variable is a variable that changes either on its own, or you purposely change it. For example, you can control the amount of light, environmental temperature, and humidity in which a plant is grown.
The goal of an experimental investigation is to determine how changes in an independent variable affects another variable, which is called the dependent variable.
Remember: When designing an Experimental Investigation it is important that you only have one independent variable and one dependent variable. All other variables must be controlled, meaning they must stay the same.
FYI: Controlled variables are not the same as a Control for your Investigation. The following will explain this.
Start Experiment Design:
I want you to understand some of the thought processes for designing an experiment that meets Science Fair Project requirements.
1. You need to have a purpose for your investigation. At this point you may not know exactly what you want to do, but let’s assume you want to work with plants. I’d search the web and find different project ideas about plants.
Let’s assume you decide to investigate how light affects plant growth. At this point you need to write a basic purpose. I point out that this might only be a BASIC Purpose, meaning you may need to improve it.
Basic Purpose