Activity

Seed germination and gravity

Summary
Bean seed are planted at different angles, to test which way the roots and shoots grow. Done as a demonstration.
Science content
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Biology: Life Cycles (2)
Biology: Sensing, Organ Systems (4, 5, 6)
Lessons activity is in
Materials
  • Jar for each set up
  • coffee filter
  • Paper towels
  • Water
  • 3 or 4 large bean seeds (e.g. broad bean) per jar
Procedure

What might affect the direction that roots grow?
(Students might suggest water, darkness....)

Put some beans in a jar at different angles to test which way the root and shoot grows each time:
Make a ring of coffee filters paper towels inside the jar, and stuff the centre with more paper towels.
Add water to the paper towels until they are wet and there is a small puddle at the bottom of the jar.
Push the bean seeds between the coffee filter ring and the glass jar wall, to hold them in place, each at a different angle, spread out around the jar.

One week later:
What can we conclude about something other than water and air (and darkness) that seed germination is sensitive to? Gravity.
Which way up should we plant a seed? (Doesn’t matter)

Results:
The roots always grow downwards, then the shoot upwards.
The seeds are uniformly wet and exposed to light, so they use gravity to determine which way to grow.

Notes

Apparently, this can be set up with a pin through the bean.
The lid can be rested on to keep water evaporation to a minimum, while allowing air to get into the jar.
This is a good activity to show the results of after other germination factors have been determined.

Grades taught
Gr 3
Teaching site
Gordon Elementary