Lesson Title: How Do Plants Know Which Way to Grow? "Tropisms"
This lesson investigates whether plants use the force of gravity to help them know which way to grow. Students gain a better understanding of plant behavior and learn how to apply the scientific method.
• Explore the effects of gravity on plant growth.
• Apply the principles of experimental design,
data collection, analysis and presentation.
Professional Development Training Module for This Lesson
Lesson Activities and Sequence
Space Garden: How Do Plants Know Which Way to Grow?
Students will set up and conduct an experiment to demonstrate the effects of gravity on plant growth. They will consider the difficulties of designing an experiment that separates the effects of stimuli (light and gravity) that have similar responses (directional growth). While slow rotation of seedlings can cancel the effect of gravity, faster rotation can create centrifugal force to compete with it. But equipment for such experiments requires significant construction and expense. A simpler technique for demonstrating gravity is to change the orientation of seedlings germinated in the dark, as will be done in this activity. Students will also consider the problem of controlling variables in order to ensure that the effect seen is the result of the variable being tested.Keywords: adaptation, gravitropism, photosynthesis, survival, phototropism, light waves, gravity, light
National Science Education Standards, NSTA
Science as Inquiry
• Understanding of scientific concepts.
Common Core State Standards for Mathematics, NCTM
Operations and Algebraic Thinking
• Analyze patterns and relationships.
Measurement and Data
• Represent and interpret data.