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We have learnt in class that light sources are those objects that give out their own light, e.g. the sun, a light bulb that is switched on, lightning, fireflies and even some kind of mushrooms.

At night, the main light sources are the stars and the moon.  But is the moon really a light source?  Read through the following websites to know the answer.

http://www.woodlands-junior.kent.sch.uk/time/moon/facts.htm

http://www.blurtit.com/q340382.html (just read the first comment)

Athletes train their body so that their lungs can take in more air in a breath.  This increases the capacity for the body to bring more oxygen to the different parts of the body (in this case, especially the muscles) between breaths. 

The respiratory system works closely together with the circulatory system.  The respiratory system brings in oxygen from the atmosphere into the body, while the circulatory system brings the oxygen to the different parts of the body.  The two systems also help bring one of the waste products of respiration–carbon dioxide–out of the body.

If you have traveled to any H1N1 affected countries on or after 22 June, please stay at home for 7 days to monitor your health.

If you are feeling unwell, please see a doctor immediately. Be socially responsible and do not come to school.

Remember to bring your ODT and handbook to school everyday, and take your temperature at home before coming to school every morning.

Your parent/guardian should have received a letter from the school regarding the H1N1 precautionary measures that has been put in place.  Please remember to fill in the enclosed Travel Declaration Form, signed by your parent/guradian, and bring it to school on Monday. 

For more information, please refer to the press release by MOE:
http://www.moe.gov.sg/media/press/2009/06/precautionary-measures-h1n1.php

Water in small amounts is transparent to our eyes, but large bodies of water appear blue.  Under certain circumstances it can appear multi-coloured.  Here’s an easy-to-read article on the colour of water.

http://www.webexhibits.org/causesofcolor/5.html

As a revision for the P5s and preview for my P4s:

Here’s a video on wayang kulit, a traditional Indonesia art of shadow dancing.

Questions for reflection:

1. What are the (three) things needed to have a wayang kulit show?
2. In a show like this, the audience is sitting on the side of the screen opposite to the light source.  What kind of material would be suitable to be used as the screen, and why? (Hint: what is being projected onto the screen?)

I think I’ve announced this a few times in class, but just in case:

P5 work: Heredity and Reproduction (Unit 1) and Reproduction in Plants (Unit 2)

P4 work: Light (under the “Energy” theme)

Some questions for thinking:

• Which part of the plant grew first? Why do you think it is important for that part to grow first?
• Living things need air, food and water to grow.  A seed does not have leaves, so it cannot make its own food.  Where does the food come from?

The roots of the plants grow first, and it always follows the pull of gravity.  The seed will sprout upwards towards the light source.  That is why we don’t have to worry how we plant the seed–it will always manage to grow in the right direction.

Here’s wishing everybody a very happy, prosperous and blessed Lunar New Year!  Have a good break, and don’t forget to come back to school on Wednesday! 🙂

Humans reproduce sexually because it needs a sperm from a male and an egg from a female to fuse together before new life can begin.  Some organisms reproduce asexually, that means, reproduce by cloning themselves and therefore their offspring is exactly the same as their parent.

(Do note that this is an exaggeration of the actual process of fertilising an egg…I hope you realise that!)

Basically out of the millions of sperm, all it takes is to have one of them to fertilise the egg, and new life can begin!

Here you see the relative sizes of the sperm and the egg.

Further exploration:
http://lgfl.skoool.co.uk/viewdetails_ks3.aspx?id=462
http://www.abpischools.org.uk/res/coResourceImport/modules/genome/en-flash/fertilisation.swf

Some FAQs:

Q: How do we get twins?

A: Although most of the time a fertilised egg develops into one embryo, there may be times where one egg divides and develops into two separate embryos.  From there you get identical twins (as in the two girls in the picture above).  They share almost the same characteristics.

Ovaries release only one egg at a time, but sometimes two eggs get released and fertilised by two separate sperms at the same time.  From there you get non-identical or fraternal twins instead.  They look different from each other, but still inherited the physical traits of their parents.

Q: Can humans have both sets of sexual organs?  How can that happen?

A: Organisms that have both sets of sexual organs in one body are called hermaphrodites.  They are not common among humans (about 1 in 1,000 births), but can be fairly common among other organisms, such as snails, some fishes and earthworms.  We also learnt that plants can too be hermaphrodites.  In humans, hermaphrodites are also known as intersex.  Factors such as disorders in the genetics of the sperm and egg, or by the embryos’ response to hormones.