Plants make their own food
Every living thing needs energy: the power to grow, move, and stay alive. Animals get energy by eating food.
Scientists call a living thing an organism (OR-guh-niz-um).
Plants can't hunt or shop. Instead, they make their own food! An organism that makes its own food is called a producer. Plants are producers. This is one of the most important jobs on Earth.
Photosynthesis
(foh-toh-SIN-thuh-sis) is how plants use light from the Sun to make food, a kind of sugar.
Photo means light. Synthesis means putting together.
Teaching tips
- Open with: "What did you eat for breakfast? So where does a plant get ITS breakfast?"
- Break the word apart on the board: photo (light) + synthesis (putting together).
Common mistakes
- Many students think plants "eat" soil or plant food from the store. Photosynthesis replaces that idea; slide 6 tests it directly.
Book correction
The workbook says sunlight is turned "into a different form of energy called sugar." Sugar is not energy itself; it stores energy. The slides use "make food (sugar)" here and explain stored energy on slide 11.
Quick check
About the wrong answers
- Digestion: students connect "food" with eating and stomachs.
- Absorbing food from the soil: the most common misconception about plants.
- Evaporation: a familiar science word that sounds like a plant process (water does leave leaves as vapor, but that is not food-making).
A plant's food factory
Tap each part to see its name and its job.
Stomata (STOH-muh-tuh) are tiny holes on a leaf. Chlorophyll (KLOR-uh-fill) is the green material that catches light.
Teaching tips
- Have students trace the path with a finger: water up from the roots, carbon dioxide in through the leaf, oxygen out, sugar down the stem.
- "Stomata" is plural; one opening is a "stoma."
- Chlorophyll sits inside tiny parts of leaf cells called chloroplasts. The inset shows them as green dots. The word "chloroplast" is optional at this level.
Book correction
The workbook picture shows water drops floating in the air around the trees and "sugar" arrows at ground level. It does not show that water enters through the roots and carbon dioxide through the leaves. This diagram shows the real pathways.
What goes in?
To make sugar, a plant uses two materials from its surroundings: carbon dioxide and water.
Carbon dioxide (CO2) is a gas in the air. It enters through tiny holes in the leaves called stomata. Water (H2O) comes up from the roots.
Sunlight is energy, not a material
The plant also needs sunlight. But light is not built into the sugar. It gives the energy that powers the change, like electricity powers a blender.
Teaching tips
- Ask: "Is light a thing you can put in a jar and weigh?" This helps students separate matter (materials) from energy.
- Connect to the blender: the fruit is the material; electricity is the energy.
Common mistakes
- Listing sunlight as an "ingredient" of sugar.
- Thinking soil or fertilizer is used to build the plant's food.
Note on the workbook question
The workbook asks what "two things" plants need to make sugar, with "Carbon dioxide and water" as the answer while "Sunlight" appears in a wrong choice. Since light is also needed, the Quick Check here asks for two materials to remove that confusion.
Quick check
About the wrong answers
- Soil and fertilizer: the "plants eat dirt" idea.
- Oxygen and sunlight: students mix up which gas goes in and which comes out, and count light as a material.
- Sugar and oxygen: students swap reactants and products.
Sort it: in or out?
Put each item in the right group. You will see the reason right away.
Teaching tips
- Run it as a class vote: students hold up 1, 2, 3, or 4 fingers for the group before you click.
- The soil item uses a real, famous experiment: in the 1640s, Jan Baptist van Helmont grew a willow tree for five years. The tree gained about 164 pounds, but the soil lost only about 2 ounces.
Common mistakes (built into the items)
- Soil is the plant's food.
- Fertilizer ("plant food") is the plant's food. It provides minerals, not energy.
The photosynthesis equation
An equation shows what goes into a reaction and what comes out. A reaction is a change that makes something new. What goes in are reactants. What comes out are products.
In words: carbon dioxide + water → sugar + oxygen. Tap each part to learn more.
Book correction
The workbook shows CO2 + H2O → C6H12O6 + O2, which is not balanced. The balanced equation is 6CO2 + 6H2O → C6H12O6 + 6O2. The workbook also labels the product "Sugars"; the slide uses "glucose (sugar)."
Teaching tips
- Students do not need to balance equations. Just say: "The big 6 means six of each. No atoms are lost or made; they are only rearranged."
- Read the arrow aloud as "makes" or "turns into."
- The workbook refers back to reactants and products from Week 5.
Quick check
About the wrong answers
- Only the products: students often focus on what gets made and forget the left side.
- How fast a plant grows: confusing an equation with a measurement.
- Which plants can do it: confusing the process with the organisms.
Simulation: light and the leaf
Move the slider to change the light. Turn water and carbon dioxide on or off.
Watch the oxygen bubbles and the sugar meter. What happens in the dark? What happens when one material is missing?
What students should notice
- No light: no bubbles and no sugar.
- More light: more bubbles, but above about 70% the rate levels off. Something else (like the amount of carbon dioxide) becomes the limit. Real plants behave this way.
- Water or carbon dioxide off: photosynthesis stops, even in bright light. Both materials are needed.
This is a simplified model; the numbers are not real measurements.
Home experiment 1: floating leaf disks
Can you see a leaf making oxygen? Tiny leaf circles will show you.
Teaching tips
- This is a classic, reliable activity. The baking soda adds carbon dioxide to the water. The soap helps the water soak into the leaf.
- Removing the air with the syringe (no needle) is the tricky step. Pull the plunger while covering the tip, then release. Repeat 2 to 3 times until disks sink.
- Disks in bright light usually start floating within 10 to 20 minutes.
- The dark cup is the control for light. Everything else stays the same.
Common mistake
Students may think the lamp's heat makes disks float. Point out that both cups have the same water; only light changes. A cool LED light works well.
Sugar stores energy
The sugar a plant makes has a science name: glucose (GLOO-kohs). Sugar is not energy itself. It stores energy, the way a battery stores energy.
The plant uses this stored energy to grow. It saves extra in its roots, fruits, and seeds.
When animals eat plants, they get this stored energy. Photosynthesis also makes the oxygen animals breathe. Without photosynthesis, almost all living things on Earth would run out of food and energy.
Book corrections
- The workbook calls sugar "a different form of energy." More accurately, sugar is a material that stores chemical energy.
- The workbook says without photosynthesis "all organisms" would run out of energy. A few living things, such as microbes at deep-sea vents, get energy from chemicals instead of sunlight. So the slide says "almost all."
Link forward
The rabbit in the picture previews Topic 2 (consumers). Don't teach consumer types yet.
Quick check
About the wrong answers
- It is the same thing as energy: repeats the workbook's wording; good discussion point.
- It makes plants sweet for insects: flower nectar is sweet, so students connect sugar with attracting insects.
- It turns into soil: students think plants feed the soil.
Photosynthesis in Virginia
Not only plants!
Algae (AL-jee) are simple living things, often in water, that also use sunlight to make food. Some bacteria can too. Phytoplankton (FY-toh-plank-ton) are tiny algae that float in water. They are too small to see.
Choose a place to explore.
The Chesapeake Bay is full of phytoplankton, too small to see without a microscope. They make food from sunlight and give off oxygen. Tiny animals eat them, and fish eat those animals.
Underwater grasses grow in shallow parts of the Bay. Like all plants, they need sunlight. When muddy water blocks the light, they can't make enough food, and they may die.
Shenandoah National Park has forests of oaks, maples, and hickories. All summer, green chlorophyll catches sunlight. In fall, the chlorophyll breaks down, and hidden yellow and orange colors show.
Every fall, families visit pumpkin patches in Loudoun County. A pumpkin's big leaves made the sugar that the pumpkin stores. That energy started as sunlight!
Book correction
The workbook says "Plants are the only organisms that can capture the sun's light energy." Algae and some bacteria (such as cyanobacteria) also do photosynthesis. Ocean and bay phytoplankton make a large share of Earth's oxygen; scientists estimate roughly half.
Local connections
- Underwater grasses (the Chesapeake Bay Program calls them SAV, submerged aquatic vegetation) are a key measure of Bay health, and water clarity is the main thing they need.
- Fall colors: yellows and oranges were in the leaf all along, hidden by chlorophyll. Reds are newly made in fall.
Quick check
About the wrong answers
- Only plants can do photosynthesis: the workbook's own statement; worth discussing.
- They are animals because they live in water: students sort living things by habitat instead of how they get food.
- They get food from fish: students reverse who feeds whom.
Word cards
Say what each word means, then tap the card to check.
Teaching tip
Pair students: one reads the word and defines it, the other flips to check. Switch roles after four cards.
Home experiment 2: light or no light?
What happens to a young plant that grows in the dark?
What to expect
- The dark seedling grows taller and thinner, with pale yellow leaves. Scientists call this etiolation.
- It grows at first using food stored in the seed. It stretches up, "searching" for light.
- Put it back in the light: in a few days it turns green as it makes chlorophyll.
Common mistake
Students expect the dark plant to be shorter. It is usually taller, but weaker and pale. This is a great surprise to discuss.
Final quiz
How the quiz works
- 8 questions. The first answer counts toward the score. Each answer shows an explanation.
- "Retake quiz" starts over with the same questions.
- Questions 3, 7, and 8 ask students to apply ideas (the soil myth, the leaf-disk experiment, and muddy bay water).
Wrap-up
Today you learned
- Plants are producers. They make their own food by photosynthesis.
- They use carbon dioxide and water. Sunlight gives the energy.
- They make sugar and oxygen.
- Sugar stores energy for the plant and for animals that eat it.
- Algae and some bacteria are producers too.
Question to think about: if plants make food, who eats it?
Exit ticket idea
Ask each student to write the photosynthesis equation in words, then circle the reactants and underline the products.