6B presentation

Do you know (1) why seawater cannot be drunk?
(2) why we should not pull out your white hair?
(3) why it is difficult to bit a cockroach?
(4) why we should stretch ourselves?

(1) No. Seawater has a high concentration level of salt and minerals. Our body has to remove the excessive salts and minerals through sweat (汗液) and urine (尿液), through which more water is lost, thus greatly increasing the workload of kidney (腎).

(2) No. Pulling out hair hurts our hair follicles (毛囊). The production of melanin(黑色素) will be further reduced. More black hair will turn grey and look unhealthy. To alleviate the situation, we could take in more iodine (碘) and have adequate rest.

(3) Scientists found that before anyone taking any action to catch a cockroach, it has escaped already. There are 440 wind detectors(偵測器) on a cockroach’s tails. They are very sensitive to wind movement and speed.

(4) If we sit or stand still, in addition to intense mental activities, our brain lacks oxygen. After stretching ourselves, our brain has more exercise and takes in more oxygen, resulting in improvement in concentration.