Ten scientific facts your high schooler needs to know

A girl looking at a pendulum.

Revealing the mysteries of life through science starts with knowing the basics.

1. Plants make their own food

Plants use carbon dioxide and water to form oxygen and a sugar in a process called photosynthesis.

That sugar can be used for two purposes by the plant:

  • to form the more complex chemicals that make up their cells so the plant can grow
  • in a process called respiration, which provides food for the plant's daily survival.

2. Energy transformation is needed to make things happen

Nothing happens without energy transformation. For something to happen, energy needs to be changed from one form to another. For example, a torch gives off light because chemical energy stored in the battery is converted to electricity, which is converted to light in the globe. When the battery is removed, there is no energy to be converted into light. Without energy, nothing will happen.

3. An unbalanced force changes the motion of an object

An object will keep doing the same thing (not moving or moving at a constant speed) unless the forces on it speed it up or slow it down.

These forces can occur from:

  • something pushing or pulling it
  • a non-contact force (such as gravity)
  • a retarding force (such as friction or air resistance).

4. An ‘empty' glass isn't empty

Take an empty glass, turn it upside down, and put it under water. Now tilt the glass toward the right way up. Air comes out of the glass and bubbles to the top of the water. Some water partly fills the glass to replace the space taken up by the air in the bubbles. Air is a gas. It weighs something and takes up space just as liquids and solids do.

5. Water can be a solid, a liquid or a gas

If we keep heating water in a saucepan it will eventually boil dry. The liquid water has become a gas. However, if we put a glass lid on the saucepan, we see drops of water form on the glass. The gaseous water has turned back to a liquid. Similarly, we can freeze water to turn it into ice. When we heat the ice, it will turn back to water. It all remains H2O, the same chemical irrespective of its state.

6. Living things are different from non-living things

There are some things that all living things do. Anything that does not do all of the following actions is not a living thing.These include:

  • using energy
  • producing waste
  • responding to their environment
  • reproducing
  • growing.

7. Living things can be classified into groups

There is a wide range of living things. The largest trees are more than 100 metres tall and weigh about six million kilograms. Bacteria are about one-millionth of a metre long and weigh less than one-billionth of a gram. To deal with the range of species, scientists classify living things into groups based on common characteristics. That is, all things with similar features are classified into a specific group.

8. There are living things that are too small to see

All living things are made up of cells. Most cells are too small to see without a microscope. A person begins life as one cell, but by the time they are born they are made up of more than one-thousand billion cells. Some living things such as bacteria are made up of only once cell.

9. Not all natural resources used by living things are recycled

Carbon, nitrogen, oxygen and water are important resources that living things need to survive. Once these chemicals are used by living things, they are recycled and returned to the environment, ready to be used again. For example, carbon is drawn from the atmosphere by trees and plants for food through the process of photosynthesis. When the plants die, some of the carbon is returned to the soil. Eventually the soil carbon breaks down and is released back into the atmosphere. Activities by humans can disrupt these cycles.

10. Earth revolves around the Sun and the Moon revolves around the Earth

Many observations can be explained by understanding the motion of the Sun, Earth and Moon.

  • Seasons: the Earth is tilted so the Southern Hemisphere is closer to the Sun in January than the Northern Hemisphere (our summer). When the Earth revolves to the other side of the Sun in July, the Southern Hemisphere is tilted further away from the Sun, so less energy from the Sun reaches it (our winter). Therefore, in the Southern Hemisphere it is warmer in January than in July.
  • Phases of the Moon: we see the Moon because the Sun's light reflects off it. Therefore, half of the Moon is light and half is dark. A full moon occurs when the entire light side of the Moon is facing the Earth. A new moon occurs when the Moon has moved half way around the Earth so that the dark side is facing the Earth. As the Moon travels around the Earth, part of the light side and part of the dark side are facing the Earth giving a full range of phases.
  • Solar eclipses: when the Moon moves between the Sun and the Earth, its shadow appears on the surface of the Earth. From this point, the Moon prevents us from seeing the Sun.


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