Seed dispersal lesson plan

Lesson plan

KS2 Science: plants

  • Estimated time: 45 minutes
  • Location: Outdoors & Indoors
  • School term: All year round
  • Key stage(s): KS2
  • Subject(s): Science

Learning objectives

  • To learn that seeds need to be dispersed to optimise their chance of survival
  • To learn that the structure of fruits and seeds relates to how they are dispersed
  • To understand that seeds can be dispersed by a variety of methods including wind and animals

Key vocabulary

Seed, dispersal, lifecycle, wings, float, encased, hooks, fruit, ovule, fertilization, survival, probability

Introduction

Give each pupil a seed large enough to write their initals on (e.g. a conker or acorn). Take the pupils outside and ask them to hide their seeds.
Which animals hide seeds and why? What happens to these seeds?
Seeds have evolved over time to be dispersed (moved). An oak tree produces 50,000 acorns a year but only 2 or 3 will grow into mature oak trees. By moving away from the parent plant a seed will increase the probability of survival. How does this increase seed survival? 

Activities

How are the seeds dispersed? Ask a volunteer to stand on a chair and throw a sycamore seed in the air and another  to gently blow a dandelion seed head. Observe closely and describe what happens to the seeds.
Imagine how much further the seeds would travel on a windy day. What are the features of seeds dispersed by wind? Ask for another volunteer to be an animal and attach some seeds with hooks (such as burdock seeds), to their clothing. You could use ping pong balls with velcro dots attached, to demonstrate the same effect. Ask them to jump up and down, the seed will remain firmly stuck until the 'animal' scratches itself. Online video clips will illustrate this further.
Some seeds are encased in a fruit which is tempting for animals (and birds) to eat. Is this the end for the seed? Think about what will happen next to all the dispersed seeds?
 

Most likely to? In groups, explore and decide from a selection of seeds, which is their most likely method of seed dispersal. Base this on catagories such as size, weight, shape, hardness and colour.  Use these characteristics to sort the seeds. Are there any common findings for seeds dispersed by wind or animals?
Use the resource make a seed spinner. Can you improve the design to make your seed travel a longer distance? Can you add features you have discovered in your investigations into seed dispersal and produce the perfect seed? 

Decide how you could record your findings.
What will you measure? Think about distance the seed can travel or time taken to reach the ground.
What are the variables that you could change? Think about the weight and size of the seed.



 

Plenary

Go back outside to find the seeds hidden at the beginning of the session. It is surprisingly difficult to find them all. Ask pupils to think of an advantage and disadvantage of seed dispersal by animal.
In their opinion, who would win the fight for survival - wind or animal dispersed seeds?
Research: How else can a plant disperse it's seeds? Find examples to share with each other.


Essential information

  • Seeds are formed when pollen from the male part of the flower, lands on the female part of the flower. Fertilization takes place and the ovule develops into a seed.
  • A fruit is a seed bearing structure that develops from the ovary of a flower.

Resources:

Large seeds (such as conkers and acorns)
Sycamore seeds, dandelion seed heads
Seeds with hooks
Seeds with attractive fruits (such as cherries)
A selection of seeds for the 'most likely to..' activity
Materials for Make a seed spinner activity

Differentiation

Less able
Investigate sizes of seeds in the world. How are they dispersed?

More able
Find out about the Swiss inventor George de Mestral. How did this topic inspire his invention?

Assessment questions

  • Why do seeds need to move?
  • How are seeds dispersed?
  • What features of seeds make them suited to dispersal by wind or animal?
  • Is it more important for a seed to reach the ground quickly, or travel further?

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