Mini Lesson Plan: Photosynthesis
What do we need to grow, and jump, and run and think? We need energy! And we get this energy from food that we eat three times a day.
Sometimes I wonder…plants grow too, but I have never seen a plant eat anything. Have you? In that case, where do they get their energy from? Let Miss Twinkle (and a series of experiments) tell you!
Activity 1: Twinkle Trails Episode 9 — Photosynthesis
Miss Twinkle and class are back at it (learning) again! Join them in the LittleLives garden and learn about what keeps plants busy all day long!
What happens within a plant during photosynthesis:
- The leaves of a plant absorb sunlight, air, and water.
- The energy from the sunlight is used to convert the air and water into sugar (“plant food”).
FYI: Sugar is broken down into usable energy when the plant needs energy. Raw sunlight energy is not in a state that can be used by the plant.
Let’s try to remember all the ingredients that plants need to make “plant food”!
Print out this worksheet and fill in the blanks with each factor that plants need for photosynthesis!
(top to bottom: sunlight, air, water)
Activity 2: Sunlight
What would happen to you and me if we don’t eat? We would die after a few days. If a plant goes a few days without food, it would die too! But how can a plant possibly go without food if it makes its own “plant food” within itself? (Hint: by taking away its “plant food” ingredients)
In this activity, we’re going to take sunlight away from a plant and observe what happens.
Set-up:
- Obtain two leafy plants of the same species.
- Mark one plant ‘Sunlight’, and the other ‘No Sunlight’
- Place ‘Sunlight’ near a window where it will receive plenty of light.
- Cover ‘No Sunlight’ with a black plastic sheet or cloth, and place it in a dark cupboard.
- Check on both the plants after two to three days.
Results
‘Sunlight’ should be healthy and thriving. Meanwhile, the leaves on ‘No Sunlight’ should be drooping, withering, and dull. Without sunlight, plants do not have the energy to combine air and water to form “plant food”. Thus, plants do not photosynthesise at night.
Why did ‘Sunlight’ stay healthy even at night?
Plants usually store some “plant food” in their leaves and fruits, which can sustain them overnight. However, after a long period of not being able to photosynthesise, ‘No Sunlight’ would have run out of its reserves and begun to die.
Why humans cannot photosynthesise
Why can’t we photosynthesise? Rather, what gives plants the ability to photosynthesise? The answer: their green colour! But that doesn’t mean that if you paint yourself green and plant yourself in your backyard, you will be able to photosynthesise.
Plants have a special substance, chlorophyll, in their leaves that gives them their green colour. This substance facilitates the process of using the energy in sunlight to form sugar.
Plants grow towards sunlight
It may seem like the only direction plants grow in is ‘upwards’. In reality, plants grow towards sunlight. Most of the time, sunlight is directly above the plant, so it grows straight. But sometimes, when there are obstacles blocking out the sunlight, the plant will grow around in order to expose its leaves to as much sunlight as possible.
Help the little plant get through this dark, dark maze and reach the sunlight!
Activity 3: Water
We all know that if you pour water, it will go down — not up. But when the roots of a plant absorb water, the water travels up, through the roots, up the stem, and into the leaves. How?
Imagine that the plant is like a straw. Just like we suck water up through a straw, the plant draws water up from the soil to its leaves through a sucking motion. Now, let’s watch this in action!
Set-up:
- Fill a cup with water.
- Add a few droplets of food colouring and stir the mixture.
- Place a few stalks of celery in the coloured water
- After an hour or two, take the celery out and cut it.
The blue dots you see on the cross-section of the celery are where the “straws” of the celery are located.
For a cool souvenir to bring home, try this experiment with white flowers (white roses, carnations, lilies). Place the stem of the white flower into coloured water and watch the magic happen!
Activity 4: Air
Our atmosphere consists of a whole range of different gases. But the one gas that all living things need to survive is oxygen. As humans, we breathe in oxygen, and breathe out carbon dioxide. This process is called respiration.
However, the amount of oxygen in our atmosphere is limited. We continuously use up oxygen, but we never run out of it. Well, this is thanks to photosynthesis!
During photosynthesis, plants breathe in carbon dioxide and breathe out oxygen. In the process, they replenish our supply of oxygen (and their own supply of oxygen) and keep us alive!
Note: Plants undergo both photosynthesis and respiration. When sunlight is present, it undergoes both processes at the same time. When sunlight is not present, it undergoes only respiration.
Let’s test it out!
- Place a leafy plant near a window with plenty of sunlight.
- Water the plant.
- Tie a plastic bag around it, or place it under a glass container. This is so that the plant will not receive any air from outside the container.
- Check on the plant the next day.
The plant wouldn’t have died because it continuously replaces both the oxygen and the carbon dioxide in its container. Thus, the plant is able to undergo both respiration and photosynthesis to keep itself alive!
Another cool way you can test this out is by creating a terrarium with your friends! A terrarium is completely sealed so that no water or air from the surroundings can enter the plant’s isolated environment. You can check out our Mini Lesson Plan on The Water Cycle to see how we built our terrarium!
Feeling energised by your new wisdom? Before you go outside and load up on sunlight, share this Mini Lesson Plan with your fellow teachers, parents, grandparents, grandteachers(?), and kids!
PHOTOS
LittleLives Inc.
Pixabay
Tinker Lab
Mini Gardeners
Babble
SOURCES
LittleLives Inc.
