Energy Sources

Every time you switch on a fan in your HDB flat, you are using energy. Every time a plant grows in your school garden, it is using energy. But where does all that energy come from? Here is the surprising truth: for almost every living thing on Earth, the answer is the same — it starts with the Sun. Understanding where energy comes from, and whether it will last, is one of the most important ideas in PSLE Science.

Parents: let your child predict before each reveal, especially the sorting game below — saying the keyword out loud is how it sticks. Five minutes of active sorting beats twenty minutes of reading.

By the end you will be able to explain why the Sun is our main energy source, tell the difference between renewable and non-renewable sources, name the fossil fuels, and say why we should save energy and switch to cleaner sources. Four big ideas — let us tackle them one by one.

The Sun: the energy behind almost everything

Think about what you ate for breakfast this morning. Rice, bread, an egg, or a banana — every one of those came from a plant or from an animal that ate plants. Now ask yourself: how did those plants grow? They grew by soaking up sunlight during photosynthesis. Without the Sun, plants cannot make food. Without plants, animals have nothing to eat. Without animals and plants, there is no food for you either.

The same is true for almost every living thing on our planet. Even the fish in the sea eat tiny plants that need sunlight to grow. The Sun is the starting point for nearly every food chain. That is why we say the Sun is the main source of energy for almost all living things.

Renewable energy sources

You have just been outside at a playground. Was there wind? Will there be wind again tomorrow? Of course — wind does not run out. Now look up at the sky on a sunny day. Will the Sun rise again tomorrow? Yes. What about the rivers and reservoirs around Singapore — will water keep flowing? Yes.

These three — sunlight, wind, and moving water — have something in common: we can use them to generate electricity today, and there will still be just as much of them tomorrow, next year, and a thousand years from now. We call them renewable energy sources.

Singapore uses solar panels on HDB rooftops to capture sunlight. Countries with strong winds use tall wind turbines. Countries with large rivers build hydroelectric dams — hydro means water. All three are renewable.

Non-renewable energy sources and fossil fuels

Now imagine digging up a lump of coal from the ground and burning it. Once it is burned, it is gone. The coal took millions of years to form underground from ancient plants and animals that died and were slowly compressed. Humans are burning it in decades. Once it is all used up, it will not come back in our lifetimes — or in our great-great-grandchildren's lifetimes.

Coal, oil, and natural gas are all formed this way. We call them fossil fuels. Because they took so long to form and we are using them much faster than they can be replaced, they are called non-renewable energy sources.

Burning fossil fuels also releases gases that harm the air — another reason to use less of them.

Sort the sources — try the experiment

Now try sorting all six energy sources yourself. Pick one, then drop it into the right bin. The sim gives you feedback the moment you place it.

🔬

Sort the Energy Source: Renewable or Non-Renewable?

🤔 Predict first: Will the wind ever run out as an energy source?

YesNo

Why we should save energy and use cleaner sources

Here is a simple sum. If we keep burning coal, oil and natural gas at today's speed, they will run out — and future generations will have nothing. Burning them also releases gases that warm the planet and dirty the air. Both problems point to the same two solutions:

1. Save energy — use less electricity at home (switch off lights, use fans instead of air-con at lower settings, unplug chargers) so we burn less fossil fuel.
2. Switch to renewable sources — solar panels, wind turbines, and hydroelectric power give us energy without running out and without the dirty gases.

Singapore's HDB estates now have solar panels on almost every block. Schools have installed solar panels on rooftops. These are real examples of switching to cleaner, renewable energy.

Watch out — these are easily mixed up

Quick recap

🎯 Mastery check

Answer all 8 — your progress is saved on this device.

1. A lion eats a zebra. The zebra ate grass. The grass grew using sunlight. Which organism is the original source of energy in this food chain?

   The lionThe zebraThe Sun (via the grass)

2. Which THREE of the following are renewable energy sources? (Choose the best answer listing all three.)

   Coal, oil and natural gasSun (solar), wind and moving waterSun (solar), coal and wind

3. Coal was formed from ancient plants buried underground millions of years ago. Why is coal a non-renewable energy source?

   Because it is dug from the groundBecause once we burn it all, it cannot be replaced quickly enough — it will run outBecause it produces electricity

4. Name the three fossil fuels.

   Solar, wind and moving waterCoal, oil and natural gasCoal, wind and oil

5. Singapore installs solar panels on HDB rooftop. Which best explains why this is a good idea?

   Solar panels look nice on buildingsSolar energy is a renewable source that does not run out and does not produce harmful gasesSolar panels are cheaper than coal

6. A student says: "We should use more fossil fuels because they give us lots of energy." Give TWO reasons why this is a bad idea.

   Fossil fuels are expensive and hard to findFossil fuels will run out (non-renewable) and burning them harms the environmentFossil fuels do not produce enough energy

7. A hydroelectric dam uses the movement of a river to generate electricity. Which type of energy source is this?

   Non-renewable, because dams are large and use a lot of material to buildRenewable, because moving water does not run outNon-renewable, because water can evaporate

8. Your family switches off lights when leaving a room and uses a fan instead of air-conditioning when it is cool enough. How does this help the environment?

   It makes the house quieterIt saves energy, which means less burning of non-renewable fossil fuels and less harm to the environmentIt makes electricity bills lower, which is the only benefit

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