8th Grade Science Review

Guys, here's some help for the ESSAY questions.

1) Why is it good for ice to float?

If ice didn't float, it would sink. If that were to happen, ice would slowly get thicker and thicker until we'd have no drinking water left. [you have a little drawing in your notebooks about this too]

2) History of the 1st law of thermodynamics + examples.

Names and dates aren't exactly necessary for this one, but it's important that you understand HOW it happened. At first, scientists believed heat was a substance, but after a few years of experimenting and research, they realized that heat is interchangeable. This led to the realization that all energy in the universe is constant and interchangeable. Mechanical energy can produce heat energy, chemical energy can produce mechanical energy, etc. With this in mind, you need to be able to look around a room and find at least 2 examples of this law in action.

3) The 2nd law of thermodynamics:

"Everything goes from order to disorder." This means that, if left alone, things will always become less organized. With this in mind, the students should be able to describe what a place would look like after being left alone for centuries.

4) How refrigerators work:

You drew this on their notebooks with an explanation. You should know this one from that. But basically, as the refrigerant goes from a thin, high-pressure tube [found in the back of the fridge] to a wide, low-pressure tube [inside the fridge], it will transform into a gas, and as that occurs, it will create a cooling effect inside the fridge because that transformation will absorb any heat that may be inside the fridge. 

5) How birds' bodies are designed for flight:

In class we looked at the bodies of birds and talked about how every system works to create enough energy for flight. For this question, you should be able to look at your notes and get a good idea about what to write. Think about how the digestive system, the skeletal system, the muscular system, etc. help the bird fly. You should be able to come up with a good answer.