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Archive for January, 2011

There is a more interesting activity to explain how fireworks are made, without actually exposing the students to greater risk. ( I have to say greater because there is still a risk doing this practical.) How do fireworks create that spectacular fountain of colours and amazed young and old alike. The gorgeous exploding mixture of purples and reds, blues, yellows, greens, lilac, is just a salt away. Chemistry has loads to offer when it comes to interesting activities, and this is one of those. (more…)

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You could do a simple demo to show that gas expands as you heat it.  If a substance is heated, the molecules in that substance start to move and soon take up more space – IT EXPANDS. (more…)

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This activity investigates the rule of reflection, which focuses on obtaining, collecting, and considering evidence. The students should learn and remember the basic terms that are associated with the law of reflection.

When you look in a mirror, you can see a reflection of yourself.  If you look at texts on the newspapers or magazines, they appear to be reversed, which is the way light is reflected by a mirror. How can we investigate this phenomenon? What is reflection? What is the law of reflection? (more…)

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The sun is a primary source of the Earth’s energy.  In fact, the energy to heat us up travels from it at the speed of light, just like the light rays.  This particular energy rays that cause the most heating are called infra-red rays.  These are also light rays but of longer wavelength. Since it is a light ray, it can also be reflected by mirrors. This is where the idea of ‘solar furnace’ comes about, particularly in hotter parts of the world where solar furnace is used, to collect the rays from the sun and focus them on to kettles or cooking pans. (more…)

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The sky is blue especially during bright days due to Rayleigh scattering. This scattering is the elastic scattering of electromagnetic radiation including light, by particles much smaller than the wavelength of the light. It can happen notably when light travels through gases or air. Rayleigh scattering of sunlight results in diffuse sky radiation, which is primarily the reason why the sky is blue and the sun look yellow.

As light travels through the atmosphere, most of the longer wavelengths just pass through straight away whilst some of the red, orange and yellow light, is affected by the air. Much of the shorter wavelength light, like the blue wavelength, is absorbed by the gas molecules, which is then radiated in different directions. It scattered all around the sky and so the blue colour seemed to occupy much of the sky.

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QUICK WITS

  • Although plants do not have nerves, they do use electrical impulses for coordination.  These impulses are like the humans, but much slower.  The Venus flytrap plant is a good example.
  • A single photon of light – the smallest quantity you can get, is enough to stimulate a rod cell. (more…)

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How can you get salt from a rock salt or seawater? This is a simple classroom demo to show that the common salt in the kitchen is mined from underground or can be taken out from the seawater. (more…)

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