What Makes a Healthy Plant?
In this lesson, students predict the effects of water,
light, and soil on the development of a plant and then design an experiment to test their predictions.
In developing our lessons and activities, we made some assumptions about the hardware and software that would be available in the classroom for teachers who visit the LETSNet Website. We assume that teachers using our Internet-based lessons or activities have a computer (PC or Macintosh) with the necessary hardware components (mouse, keyboard, and monitor) as well as software (operating system, TCP/IP software, networking or dial-up software, e-mail and a World Wide Web client program, preferably Netscape, but perhaps Mosaic or Lynx). In the section below, we specify any "special" hardware or software requirements for a lesson or activity (in addition to those described above) and the level of Internet access required to do the activity.
Have the students name some of their favorite foods. How many of them are derived from plants? (Cereals, pasta, flour, bread, fruits, vegetables, etc.) Can they name any animals that eat plants? What types of plants are a common food for animals? This discussion should lead to a collective sense that plants are a vital element in the food chain.
Discuss what plants need to grow? How much water, soil, and sunlight do plants need for healthy growth?
Ask students to predict what might happen if a plant gets too much or not enough water, soil, or sunlight?
Help students to discuss ways to test the variables that might affect plant growth. Discuss the need to control variables in a scientific experiment in order to measure the effect of other variables on the outcome. Talk about controlling for confounding variables by keeping some things constant while changing or varying others.
Divide the students into groups and ask each group to choose a variable to test for in their plant growth experiment: water, light, or soil.
Each group should outline their experiment in their Science Journal and list the controlled variables and the one variable they will be testing for (i.e., if a group is testing for light, they would control water and soil). Diagram the steps they will take to control the variables, for example:
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