Bending Plant Roots with Gravity

Overview

How do plants know which way is up or down? How does this affect which direction their roots will grow? In this lesson plan, your students will investigate how changes in a plant's environment, like the direction of gravity, affect the shape of its growing roots over a period of several days.

NGSS Alignment

This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:

• MS-LS1-5. Construct a scientific explanation based on evidence for how environmental and genetic factors influence the growth of organisms.

This lesson focuses on these aspects of NGSS Three Dimensional Learning:

Science & Engineering Practices	Disciplinary Core Ideas	Crosscutting Concepts
Constructing Explanations and Designing Solutions. Construct a scientific explanation based on valid and reliable evidence obtained from sources (including the students' own experiments) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.	LS1.B: Growth and Development of Organisms. Genetic factors as well as local conditions affect the growth of the adult plant.	Cause and Effect. Cause and effect relationships may be used to predict phenomena in natural systems. Phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability.

Materials

Materials for teacher preparation and demonstration:

• A variety of plant seeds
• A growing plant

Materials per group of 2–4 students:

• Plastic zip-lock sandwich bags (3)
• Permanent pen (1) or a pen and tape
• Paper towels (3 full sheets or 6 half sheets)
• Water (0.25 cups)
• Radish seeds (15)
• Strong tape
• Large cardboard box (1)