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PROFESSOR: I wanted to make a few comments on the third problem set, which was a funny puzzle. And it was intended to be entertaining and get you thinking about things related to symmetry in an amusing context. And there were two problems. The first problem had a platter on which there were arranged cherries with either two or three berries to a spray, and apples and pears. And they were either black or white, which didn't make then particularly appetizing. But in any case, there were three platters and the fruits marched around on the platter. And the puzzle was, what would be the fourth platter in the sequence? This didn't involve symmetry in any sense of the word. But yet, what was going on from picture to picture was a mapping of the motifs from one location to another. Not just rotation or translation or anything nice in the crystallographic, but still they were being moved from one location to another. And just about everybody got the right answer just by de...

STEPHEN CARPENTER: What I wanted to demonstrate is how this press works. I want to show how to make a proper water filter. And this is a ceramic water filter that I'm going to create here. And that's essentially a focus of the first talk. This is bisque-fired filters made with clay and sawdust. Dry clay, dry sawdust, about 50/50. And when the sawdust burns out, it leaves pores. Now, the clay is naturally porous, but the sawdust allows for more porosity, and so the water can flow through. If you have water that's contaminated with microbes and pathogens that might create things like cholera, E. coli, Giardia, you can put that water into this filter. It will filter about one to three liters an hour. And that water is rendered about 95% free of those contaminants. If we add a small amount of colloidal silver to the filter by brushing it on-- usually, it's a less than a gram with about 500 milliliters of water. That silver acts as a natural antimicrobial and w...

AUDIENCE: I wanted to give an answer to 2. MICHEL DEGRAFF: OK, yeah. AUDIENCE: So to both parts-- like, one of the parts was, like, how do the discourse of power affect the role. Like, I don't know, how do discourse of powers affect how I choose to, I guess, identify or how I choose to make decisions related to language. For example, I'm from Mexico and I speak Spanish, but at the same time, part of wanting to be more Mexican is acknowledging that we have native languages. Like, Spanish is a language that was imposed on Mexico-- people who were from the land of Mexico. And it sounds like, because I want to, I don't know, get to know that part of Mexico, that motivates me to try to learn some of the native languages like [INAUDIBLE].. Or just because I feel it's like I could be more-- RACHEL: More Mexican? AUDIENCE: Yeah, more Mexican. MICHEL DEGRAFF: OK. AUDIENCE: Yeah, I'd even add that in these discourses of power, how they affect how we see our role...