21st Century Science - Topic summaries

The 4th Year 21st Century science class taught the whole unit on Radiation to each other. Here are their summaries.

Lucas
Laura and I taught a lesson on the pages 36, 37 and 38. We taught the class about the three ways of representing electromagnetic radiation. In science, radiation simply means something that carries energy, and spreads out from its source. The sun is a very hot object so it radiates lots of energy, in many parts of spectrum. The suns most energetic radiation is X-rays. Human bodies are warm, so they radiate small amounts of energy, all of it infrared radiation.

We taught about photons, high energy, low energy and waves. We also taught about rays and the idea of ‘radiation.’ With radiation we learned about the source and the receiver. We also taught that ionising radiation is harmful. We told the class that living cells are complex things and they can be damaged by ionising radiation in two ways- even a small amount may damage the cells DNA. It may then grow in an uncontrolled way-a cancer tumour forms. Large amounts of radiation can kill cells. We used examples to describe things such as microwaves and potatoes; microwaves are absorbed by cells in a potato and the cells get warmer. We also taught about ionising radiation which is when chemical changes happen when some types of electromagnetic radiation are absorbed. When ionising radiation strikes molecules, it makes them more likely to react chemically.

We made the class write down the key words and the definitions. The questions on the bottom of page 37, we made the class answer and then asked for volunteers to answer them. We then moved on the lesson and talked about the ozone protection. Ultraviolet radiation causes chemical changes to the ozone layer. When ultraviolet radiation strikes ozone up in the ozone layer, the ozone absorbs it which makes oxygen. Overall the number of ozone molecules stays the same, the chemical reaction warms the atmosphere, and ultraviolet radiation is absorbed. We looked at a map showing the concentration of ozone in the ozone layer above Antarctica. We also looked at a picture showing old fridges waiting to have ozone-destroying gases removed from their insulation and their cooling systems. We read a couple of paragraphs on page 38 about the UN taking action. We described what it is and how it took action and why.

Fran and Padwick
Mobiles always give off microwaves. These signals are simple and short and have high energy. They are capable of transmitting loads of information in short periods of time. Radio and TV use radio waves. This type of electromagnetic radiation carries the least amount of energy so is less dangerous.

Whilst it is switched on your mobile phone is constantly sending out messages to say where they are. The nearest phone mast picks up these signals and directs any messages to you. Most young people use them to keep in touch with friends and family.

Microwaves travel mainly in straight lines so you have to consider the line of sight when you use them.

Vicks and Tom
Keywords
Greenhouse Effect
Global warming
Atmosphere

Fun facts
The atmosphere is getting destroyed by chemicals. Ice is melting and raising sea levels, which destroys coastlines. The weather is mucked up now.

Summers
Our main topics were

• Radio waves
• Mobile phones
• Communications
• Infrared
• Radiation
• Radiation used in conflict