Sowing the Seeds of Germination and Scarification

Students learning about rice on a trip to the Mekong Delta, Vietnam.

Students learning about rice on a trip to the Mekong Delta, Vietnam.

This lesson plan is to be used in conjunction with our Singapore, Sedili Besar, Mekong Delta, Hoi An, Thailand or Bali experiential field trips, where young students will learn about rice, garden plants, seed anatomy, seed dispersal techniques, and unique ways that plants grow in South East Asia.

Ages 11-14

Vocabulary covered:

Seed Dispersal

Embryo (plant)



Seed Coating





1.       Topic introduction and review:

a.       Begin your lesson by having your students to play a quick game of catch phrase (where a student draws a word from a hat and must describe it without saying the word while their partner guesses) with a partner, using edible garden trees and plants that you saw on your Ecofieldtrip.

b.       Ask the students what all these plants have in common? Elicit from students that these are all plants that you saw last week on your trip.


2.       Understanding planting seasons:

Use this template for your harvest calendar!

a.       Give your students a blank calendar (pictured at right) with boxes for each month. Using different colors, have them fill in all the months they eat rice. Next, change colors and have them fill in all the months they eat watermelon.

b.       Think about which holidays they would eat watermelon (around lunar new year).

A completed calendar might look something like this…


Ask your students:

·         Do all of your fruits and vegetables grow in [your town]?

·         Where do these foods come from?

·         Do you think they can grow all year round?


c.       Have your students fill in the seasons that rice and watermelon are planted (the graphic above shows Vietnamese rice seasons, Thai seasons are Jan/Feb and Mar-Aug).


Ask your students:

·      Why do you think farmers must plant their crops at these times?


d.       Show your students the weather patterns for the areas and have them fill these in the top bar of their chart.

i.      Ask them if they see any patterns between the weather and planting.

     ii.      Explain to your students that the weather can affect how well plants can grow, some may like hot weather, some prefer wet and some prefer cooler weather.

Ask your students the following questions:

·         Where does rice grow?

·         Can you grow rice in Antarctica?

·         Where do apples grow?

·         Can you grow apples in Singapore?

·         Why don’t plants grow during the winter in the North?


c.       Explain that the freezing cold weather does not provide enough sunlight and water for the plant to survive.


Ask your students:

·         How does a seed know not to grow during this time?

·         How does a seed know not to grow when it is rainy season? Or dry season?

·         Do seeds have brains?


3.       Seed anatomy:

a.       Show your students a picture of the anatomy of a seed, see if they can label all of the parts (seed coat, embryo, cotyledon, endosperm).

A basic seed anatomy will look like this, see if your students find something similar in their lab!


·         Why do plants have hard seed coating?


b.       Explain that the seed coating is meant to prevent the plant embryo from germinating (starting to grow) in unwanted situations (during the winter, in a stomach), much like a chicken egg has a shell to protect the baby chicken while its growing. Most plants need some sort of scarification in order to get enough water and nutrients to the embryo to begin growing. This means that the seed coating needs to be broken in some way.


c.       How does the seed coat break in nature? There are many ways:

i.         Appropriate amounts of stomach acid when an animal eats a plant dissolves the seed coat (ask if they remember seeing seeds in animal poop on their Ecofieldtrips as evidence of seed dispersal).

ii.       Microbes and bacteria eat the seed coating leaving little holes.

iii.     Exposure to cold hardens the embryo and cracks the seed coating when it thaws (when a material goes from a cold to warm it expands like an ice cube turning into water).


4.       Connecting seed dispersal and germination:

a.       Have the students play a matching game using cards of different fruits and different seed dispersal methods (gravity, water, ballistic, sticking, wind, animals-covered on your Ecofieldtrip).

b.       Then ask how they think the seed coat is scarified. Students should predict that those dispersed by animals eating them will be scarified by stomach acid.

c.       Those dispersed by wind or gravity will be scarified by bacteria or cold. Plants that grow in cold climates are more likely to be scarified by cold. Plants that grow in warm and wet climates are more likely to be scarified by bacteria because bacteria thrive in warm and wet environments.


5.       Lab preparation:

Have students watch this TED video to learn more about scarification before trying it themselves.

Lab Experiment


5 Apple Seeds per group

5 Basil Seeds per group

5 Alfalfa Seeds per group

5 Hibiscus Seeds per group

(other seeds that can be used are olives, spinach, morning glory, beans, sweet pea, pomegranate, grass)


Bunsen burner


1 Nylon bag per group

Paper towels

5 Ziploc bags per group



10% Bleach solution (if desired)

Spray bottle


1.       Have your students draw the seeds and label their drawings. Be sure that they note down that this is Day 1, before scarification.

2.       Take 1 seed from each plant, place in Ziploc bag with damp paper towel folded in half. Lay out near a window, this will be the control group. Make sure each group’s bags are labelled.

3.       Repeat step 2, but this time place in a refrigerator. This will be the cold scarified group.

4.       Take 1 seed from each plant, and clip a corner with nail clipper. Make sure to clip the opposite side of the seed from where the embryo is attached. Then place in Ziploc bag with damp paper towel folded in half. Lay out near a window, this will be a bacteria/microbe scarified group.

5.       Take 1 seed from each plant, and sandpaper the seed coating of all of these. Make sure not to sandpaper too far. Place in a Ziploc bag with a damp paper towel folded in half. Lay out near a window, this will be a bacteria/microbe scarified group.

6.       Take 1 seed from each plant and put in a Nylon bag. Heat up the Bunsen burner and begin to heat up the water. The water should be no more than 90 ͦC. Place the nylon bag in the water for 4 minutes, holding it in the center with tongs. Take out the seeds, then place in Ziploc bag with a damp paper towel folded in half. Lay out near a window, this will be the heat scarified group.

7.       One week later, return to your seeds, have the students draw pictures of the germinating seeds. Note: many seeds will take longer than 1 week to germinate, in this case, replace the damp paper towel and repeat the following for up to 3 weeks.

8.       After this lab experiment, have the students determine which method worked best for each seed. Then ask them to decide which method of scarification occurs naturally for each plant. Ask them to predict which method of seed dispersal each plant would use naturally. For an added surprise, keep the seed types secret (call them A,B,C,D,E) and let them know after they made their prediction about seed dispersal and scarification methods.

Ask the students the following questions about the experiment:

·         Which of these plants grew the easiest?

·         If you were a farmer, which would you like to grow on your farm?

·         Do you think the seeds that require cold will live well in Singapore?

·         Of the seeds that did not germinate, what method of scarification do you think they needed?

For an added creative activity, have your students design a farm with each of these seeds, or a machine that will scarify them for you!