I learned many things this week, either from class or outside. There are some that are important, and there are also some that are normal, but I think the most interesting one is I learned how sound works in physics class.
      The weeks before we were trying to build a trebuchet by our own. Now we are finally back to the normal studying of knowledge, I am always interested in it. We are learning how sound travels now, sound travels by creating waves that can be transported by objects like air, wall, water... In vacuum, sound can't be heard because there is nothing it it including air. The speed of sound is about 331 meters per second, and it is much slower than the speed of light, which is the reason why we always see lightning first and hear thunder next.
      This is probably the most interesting thing I learned this week, there are many many other interesting things that we haven't found out yet. I hope our world will become more beautiful.