B. Life Systems · Growth and Changes in Plants

Why Plants Matter and How We Can Protect Them

B1.1 B1.2 A1.3 A3.1About 40 minutes

Learning goals

I can explain why plants are important to people and other living things, from different points of view.
I can explain what native plants are and how people can protect them and their habitats.
I can describe ways people harm and help plants and plant habitats.
I can name actions I can take to protect plants.
I can use the engineering design process to build something that helps a plant.

Words to know

habitat
The place where a plant or animal lives and gets what it needs.

native plant
A plant that has grown naturally in an area for a very long time, like the white trillium in Ontario.

invasive plant
A plant brought from somewhere else that spreads quickly and crowds out native plants.

perspective
A point of view; how one person or group sees something.

impact
An effect, good or bad, that one thing has on another.

engineering design process
Steps engineers follow to solve a problem: plan, build, test and improve.

A forest floor in May

In May, some Ontario forests look like they are covered in snow again. But it is not snow. It is thousands of white trilliums! The white trillium is Ontario's official flower.

A trillium can take many years to grow from a seed to a flowering plant. If someone picks the flower with its leaves, the plant may not survive or may take years to recover. Plants are important, and they need our help.

An Ontario forest floor in spring covered with thousands of white trillium flowers under tall trees. — Each white trillium has three petals and three leaves. These plants took years to grow, so we leave them for everyone to enjoy. AI-generated image

Why plants matter: different perspectives

Different people and living things see plants in different ways. Each perspective shows a different reason plants are important.

A bird: "Trees give me a place to build my nest, and seeds and berries to eat."
A farmer: "My crops feed my family and many other families. I need healthy soil, rain and pollinators."
A beekeeper: "My bees need flowers for nectar to make honey."
A carpenter: "I build houses and furniture with wood from trees."
A doctor: "Some medicines were first discovered in plants."
A city worker: "Street trees give shade on hot days and soak up rain so streets flood less."
Many Indigenous peoples teach that plants are relatives and gifts that we are connected to. For example, the Haudenosaunee Thanksgiving Address gives thanks to the plants, the medicines and the trees, along with the rest of the natural world. People should take only what they need and show respect.
Every animal that breathes: plants give off oxygen.

Different perspectives: a bird, a farmer, a beekeeper and a city worker each have a different reason that plants matter.

Native plants

Native plants have grown naturally in a place for a very long time. Ontario native plants include the white trillium, the sugar maple, the eastern white pine (Ontario's official tree), milkweed, wild columbine and black-eyed Susan.

Native plants are important because the native animals of Ontario depend on them. For example, monarch caterpillars need native milkweed, and many native bees visit native flowers.

Some plants brought from other places become invasive. They spread fast and crowd out native plants. Garlic mustard in forests and phragmites (a very tall reed) in wetlands are invasive plants in Ontario.

Human activity	Impact on plants	Harmful or helpful?
clearing land for houses, roads and stores	plant habitats are destroyed	harmful
spreading road salt in winter	salty soil harms roots of roadside plants and trees	harmful
littering and polluting	garbage and chemicals harm soil, water and plants	harmful
walking off trails or picking wildflowers	plants are trampled or cannot make seeds	harmful
planting invasive plants	they crowd out native plants	harmful
careless campfires	can start forest fires	harmful
planting native trees and flowers	more food and shelter for native animals	helpful
creating parks and protected areas	plant habitats are kept safe	helpful
composting	adds nutrients to the soil	helpful
pulling invasive plants (with adults)	gives native plants room to grow back	helpful

Some ways people affect plants and their habitats.

Actions you can take

Even a Grade 3 student can help plants:

Stay on the trail in parks and forests.
Look, don't pick wildflowers. Take a photo or a drawing instead.
Plant native plants, like milkweed or black-eyed Susan, in a garden, a pot or a school garden.
Pick up litter (with gloves and an adult).
Compost food scraps to make rich soil.
Use less paper and use both sides, so fewer trees are cut down.
Join a tree planting or a park clean-up day.
Water young trees on your street in a dry summer (ask a grown-up first).

Worked example

Let's look at one problem from different perspectives

A town wants to cut down a small forest to build a new parking lot. How might different people and living things feel?

A store owner: "More parking means more customers."
A family who walks there: "We will lose a beautiful place to walk and play."
A red squirrel: "My home and my food are in those trees!"
A First Nations Elder: "These plants and animals are our relatives. We should think about the next seven generations."
A scientist: "Trees soak up rainwater. Without them, the area may flood more."
Possible solutions: build the lot somewhere already cleared, make it smaller, keep the biggest trees, or plant new trees and native gardens around it.

Different perspectives help us see all the impacts. Good choices try to meet people's needs and protect plants and habitats.

The engineering design process

Engineers solve problems step by step:

Define the problem. What do we need to solve?
Plan. Brainstorm ideas and draw a design.
Build a model or prototype.
Test it. Does it work?
Improve it and test again.
Share what you made and learned.

Just for fun

The white trillium loves the number three: it has 3 leaves, 3 petals and 3 sepals. That is why its name starts with "tri", like triangle!

Hands-on activity

Design a self-watering planter

Problem: A seedling (maybe a native wildflower or one of your beans) will be alone for a long weekend. How can it get water while no one is home?

You need: a clean 2 L plastic bottle, a strip of cotton cloth or thick cotton string (about 25 cm), potting soil, a seedling or seeds, water, and tape.

Plan: Draw your design. One idea: a grown-up cuts the bottle in half. Turn the top half upside down (cap off) and set it into the bottom half like a funnel. Thread the cotton strip through the neck so one end sits in the soil and one end hangs into water in the bottom.
Build: Fill the top part with soil and plant the seedling. Pour water into the bottom part.
Test: Leave it for 3 days. Is the soil still damp? Did the plant stay healthy? Measure how much water was used.
Improve: Try a thicker wick, more water, or a different spot. Test again.
Share: Show your design and explain how water moves up the wick to the roots.

Safety: A grown-up does all cutting; cut plastic edges can be sharp, so tape over them. Wash hands after using soil.

One design for a self-watering planter. The cotton strip soaks up water from the bottom and carries it up into the soil.

Your turn

Give two reasons why plants are important to animals.

Give two reasons why plants are important to people.

What is a native plant? Name one from Ontario.

What is an invasive plant?

Name one human activity that harms plants.

Name one human activity that helps plants.

Why should you "look, don't pick" a trillium?

More practice: warm-up

What is Ontario's official flower?

What is Ontario's official tree?

What does "perspective" mean?

Is composting harmful or helpful to plants?

Where should you walk in a park to protect plants?

More practice: on your own

Why do native animals need native plants?

How does road salt harm plants?

Why might a city plant trees along its streets? Give two reasons.

What does it mean to "take only what you need" when picking berries?

In the engineering design process, what do you do after you test your design?

Challenge

Garlic mustard is spreading in a forest. Explain how this could affect the animals that live there.

Your school wants to make a garden that helps pollinators. Plan it: what kind of plants, where, and one way to care for it.

Your self-watering planter's soil was dry after 3 days. Suggest two improvements and explain why each might help.

Check your understanding

Quiz

Which is a native plant in Ontario?

Which action helps plants?

How does road salt affect plants?

What is an invasive plant?

A bird and a carpenter both care about trees. Why does the carpenter care?

What comes right after testing in the engineering design process?

Why is "take only what you need" a good rule for picking wild plants?

For parents and teachers

Big idea: B1.1 asks children to assess why plants matter from different perspectives and to identify ways to protect native species and their habitats. B1.2 asks them to assess human impacts on plants and choose personal actions. The self-watering planter uses the engineering design process (A1.3) and is a practical application at home (A3.1).

Accuracy notes: Picking trilliums is strongly discouraged because the plant needs its leaves and grows slowly; whether it is illegal depends on where you are (for example, it is not allowed in provincial parks, where no plants may be picked). Garlic mustard and phragmites are listed invasive plants in Ontario; removing them is a good family or school project, but learn to identify them first, ideally with a local conservation group.

Teaching respectfully: The idea that plants are relatives and gifts, giving thanks and thinking ahead for future generations appears in many Indigenous teachings, including the Haudenosaunee Thanksgiving Address. Present it as a valued way of knowing, not a curiosity.

Common difficulties: Children may think one perspective is "right". Encourage them to say what each person needs and to look for solutions that help both people and plants.

How to help: Do one real action together this month: plant a native flower, join a park clean-up, or start a compost bin. Supervise all cutting for the planter.