Echolocation

Wednesday (12/05/2010)

a) The various bats.
* There are about 1000 bats. Some kids asked a few questions.
** Yun Xin asked why bats are balck and would it be hard for bats to see around and even to see itself?
* Their eyes are as good as humans but because their ears are better; they prefer using ears to hunt food. ( I introduced briefly the 5 senses).
Shi Jie said that snakes won't eat bats easily because they are all black. Foo Soon said that's "protection" except that they can see the glowing eyes.
**Xing Tong asked why they look scary with different faces.
* I introduced a few bats and they were so amazed with their looks. Among: Spotted-bats, Ghost-faced bats, leaf-nosed bats, Horshoe bat, No-tail bat and Flying fox bat. So, basically; if kids drew different faces of bats; it should be okay.
** Yun Wen asked if crows and bats are good friends because they are black.....haaa!
Class: No....Crows will eat bats....haaa:)
* Bats are caring of their friends and relatives. They like to stay in a group and unlike snail; alone. They care for their babies just like rabbits care for their babies. Bats have wings with no feathers. Their wings are thin and is flexible like elastic rubber. Only their body has fur. Bats don't eat crows as far as I'm concern because my research says they eat bugs, insects, fish and small animals like mice. If parents have better answer; please do let me know. Thanks!

b) The smallest and biggest bat!
* I introduced numbers 1 -20 and showed them a ruler. We sang the song "1,2 Buckle My Shoes". The smallest bat is "Bumblebee bat" that is 15cm long and the weight of 10cent coin. The biggest bat is Flying Fox Bat of 180cm long and weighs 2 kg.

c) Echolocation
* Btas make 2 types of sound. One we can hear, another we can't hear because of its high frequency. This is the same as dolphins and whales.
* They scream a loud voice towards the prey like insects and thenthe echo would be bounced back. The reflected echo would determine the location and size of prey. Bats would catch with their wings or mouth. No wonder bats can eat up to 600 mosquitoes in an hour.
* I drew an insect and the kids threw a small ball towards it. The ball is the echo.

d) Sound can travel.
* Thanks to Xing Tong's book; we did this experiment. I wrapped a bowl with plastic wrapper and pour some rice grains on it. Then I put a pot nearby and hit it with a plastic ladle or spoon. The kids observed and observed. Yup.....the grains were jumping. That explains why echoloation works.