W68 Seeds
First Day
Seed Discussion
Ask students to explain what a seed is:
A seed is the part of a plant that develops a new plant once it is planted
and nourished.
Seeds come in all shapes, sizes, and types.
Some seeds are so tiny they look like dust.
Others can be as large as a basketball.
Seeds contain all the material a plant needs to reproduce.
There are two main types of seed plants:
Gymnosperms: produce naked seeds (not covered or inside fruits).
Angiosperms: produce flowers, and the seeds are inside fruits.
Seeds from flowering plants have seed coats to protect them.
Seeds remain asleep until they are given soil, water, and light.
*Warmth is usually required for a seed to grow, but this depends on the
type of seed.*
When you see the beginnings of little plants:
Place them into jars filled with soil.
Put one jar near a window, and the other in a cupboard (in the
dark).
Water both every three days and measure their growth for two
weeks.
Talk about:
Seed shape
Size
Color
Type of seeds
Remember to mention: Coconut is a seed.
Second Day
Seeds come in different sizes, shapes, and colors. Some can be eaten and
some cannot. Some seeds germinate easily while others need certain
conditions to be met before they will germinate. Seeds travel! They
spread in many different ways:
A)Gravity: Large, round, heavy fruits just drop straight off the tree onto
the ground when they are ripe, like apples and coconuts.
b) Animal: Fruits are eaten by animals, then the seeds inside are passed
as waste material, like dates. Animals may collect fruits or seeds and
bury them to eat later, but sometimes forget about them, and the seeds
germinate in their new location.
c) Explosive: Geraniums also use the heat of the sun to shoot their seeds
from the pods, like viola.
d) Wind: Wind is one of the main agencies of seed dispersal. The way it
transports seeds depends on the type of seed and where it grows. Some
seed pods face downwards, but many have their openings at the top.
These need the wind to bend their stalks enough to allow the seeds to
fall out.
e) Water: Some plants make use of water to disperse their seeds. Plants
which grow beside water often rely on water to transport their seeds for
them. They may produce light seeds which float.
Third Day
Use different pictures to introduce seed structure:
Testa: The seed coat protects the embryo.
Hilum: Scar from the seed being attached to the plant.
Embryo: The embryo is what forms the new plant.
Cotyledon: The cotyledon is the first leaf that germinates. It is filled with
stored food that the plant uses before it begins photosynthesis.
Epicotyl: The basis for the plant’s stem.
Plumule: Two leaves and a growing point.
Radical: The part of the seed where the root develops.
Then teach them what will happen when a seed is placed in the soil:
They begin to awaken as water is absorbed.
As this water is taken in, the seed’s protective coat expands,
eventually splitting open to allow oxygen inside.
The plant’s root is the first to emerge from the seed and anchors the
plant within the soil.
The root also enables the plant to absorb much-needed water and
nutrients.
Next, the young shoot begins to grow, and soon afterward, it will
develop its first real leaves.
Once the seedling has sprouted its new leaves, the plant is able to
begin making its own food through a process called
photosynthesis.
Fourth Day
Then talk about the stages of seed germination:
Seeds remain dormant (inactive) until conditions are right for
germination.
All seeds need water and oxygen; some seeds require proper light as
well.
Some germinate better in full light while others require darkness.
When a seed is exposed to the proper conditions, water and oxygen
are taken in through the seed coat. The embryo’s cells start to enlarge
first, followed by the shoot or plumule that contains the leaves and
stem.
Teach about situations that can cause poor germination:
Overwatering causes the plant to not have enough oxygen.
Planting seeds too deeply causes them to use all their stored energy
before reaching the soil surface.
Dry conditions mean the plant doesn’t have enough moisture to start
and continue germination.
Some seed coats are so hard that water and oxygen cannot get through
until the coat breaks down. Soaking or scratching the seeds helps
break down the seed coat.
Other seeds need to be exposed to proper temperatures. For
example, apple seeds will not germinate unless held at cold
temperatures for a period of time.
Fifth Day
Teach more about seeds:
Seeds serve us in at least three ways.
A large part of agriculture is about producing seeds used for food
and as materials for many other uses.
Many seeds are grown for planting, so farmers can have the best
seeds for the next crop.
Seeds are the basis of all procedures to improve plants through
breeding.
Explain that each of the foods is a part of a plant. For example:
Carrots are roots
Lettuce is leaves
Broccoli is a flower
