Students started with a jump in going over key concepts from the notes on Friday. Today in class we discussed waves, powered by wind, and their parts. We were interrrupted by a fire drill, but students were quizzed during this time on concepts they should know, earning stickers for correct answers.
Back in the classroom, we discussed tsunamis. Tsunamis are caused by underwater earthquakes and they displace water. Displacement of water causes a large wave or energy to travel through the water, but it cannot be seen at the surface until the wave approaches shallow water. (Confused? Check out the diagram to the left) Because the wave is not felt in deep water, going out to sea is one option for escaping a tsunami, getting onto land with higher elevation is another option. There are places in Japan and Hawaii where fishermen went out to sea in the morning and when they returned, their villages had been washed away.
Next we discussed tides. Tides are caused by the moon's gravitational pull on the ocean. The sun has an impact too, but the moon's impact is greater because it is a lot closer. The ocean water bulges towards the moon and causes the high tide... areas perpendicular to the bulge are having a low tide. Because the earth is rotating, each place is going to have two high tides and two low tides each day.Spring high tides are exceptionally high and really really low when the earth, sun, and moon are all lined up in a row. Click on the diagram for more information.
We finished class by discussing temperature and locations on the globe and watched some blue planet on tides, tidal bores, sand bubbler crabs that comb through sand eating macro-organisms, and bears that eat clams.
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