Week 11: The Rock Cycle

The big question for this week was, What happens during the Rock Cycle and what are its constant laws? 

Lab

First, we discussed the Sweater article. One of my big takeaways was that we have to let students lead investigations that they're really interested in, and that they might not change their mind even when their idea has been disproven. 

Next, we talked about the law of superposition and its implications and did some "practice problems" where we figured out what order a bunch of rock layers were laid in. Next, we did a sand lab. In this lab, we used a digital microscope to look at different types of sand to describe their color, shape, etc. and try to guess their origin based on their characteristics. My group and I made some correct guesses, but we were off on a lot of them. I had a particularly hard time differentiating between the wind-affected sand and the sand that was formed in the ocean. I assumed that all water-affected sand would be rounded, but that wasn't the case. 

Lecture: 

On Thursday, we talked about density and Archimedes' Law. 

Density: the amount of "stuff" for an object's size; how tightly compacted an object's molecules are. 

An object that has a density higher than 1 will sink in water; if it has a density below 1 it will float in water. 

We put cans of different sodas into water to see if they sank or floated. The Diet Coke floated because it has aspartame rather than real sugar, so it was less dense for its size. 

Archimedes' Law:  

We read a couple of stories about Archimedes' principle. The principle states that an object's weight is the same as the weight of water that's displaced by that object. For example, if you put a dog in a full bathtub, the weight of water that flows out of the tub is equal to the weight of the dog. 

We also learned the formula for specific gravity = (weight in air) / (weight in air)-(weight in water) 

And we talked about this concept with geodes. We can figure out how much of a geode is composed of crystals (as opposed to air) by figuring out its specific gravity. 

Pressbook

1. What did you learn? 

• Geodes form in the cavities in rocks. Cavities can form in igneous rock or sedimentary rock. 
• Weathering is the process of breaking down rock. Erosion is the process of moving that rock. 
• Even sedimentary rock can become metamorphic rock through heat and pressure. 
• Metamorphic rock can be transformed to magma or sediment depending on its environment, and in turn can become igneous or sedimentary rock. 

2. What was most helpful? 

• The rock cycle diagram. I was having a hard time finding a good one, and that one really helped me understand all the possible "routes" rock can take through the cycle. 
• The key takeaway about weathering and erosion, that weathering is making the mess and erosion is cleaning it up. That really helps me understand their relationship and how the two are very different. 

3. What do you need more information on? 

• I'm curious what other applications "specific gravity" has. Is this something we would use in a science classroom in the future, and how would it be used?