Friday Funnies

Once again, humor in honor of the last Friday of the month. More serious posts to follow over the weekend!

3:37 pm: Scrounging through my desk for soda money

Volunteering with SEP

One of the things that I'm really excited about is teaching. Teaching is something I did throughout high school and college, both as a tutor and a more formal Teaching Assistant. I really enjoy that "Aha!" moment, when a student has been struggling with a particular concept for a long time, and it finally clicks with them. The other thing that I am really passionate about is science outreach. There have been a number of studies exploring the reasons why people shy away from science, or why the reasons why certain groups are underrepresented in various fields. I'm not going to get into this topic too much in this post, sufficient to say that I think early exposure to science is critical. And what better way to combine early exposure to science and teaching that through volunteering in public schools!

UCSF has a program called "Science and Health Education Partnership" (SEP). The basic idea behind the program is to pair students/postdocs with a teacher in the San Francisco Unified School District. The scientist-teacher team then plans and executes a series of lessons throughout the semester. Sometime programs last a few months and the scientists teach just 4-6 lessons, whereas other programs last the entire school year. 

So far I've been involved in two semester-long programs during my time at UCSF. As a first-year grad student, I was involved in the Bio&ChemTeach program. I was paired with a 7th grade Life Science classroom, along with two other students from my graduate program. The school where we taught was ranked in the bottom 5% of schools in California, and served mostly students of Latino decent. Our lessons were designed to fit into their existing curriculum--and thus didn't really follow a theme or share continuity with each other.

One of my favorite lessons from last spring was entitled "A Day in the Life." We asked the students to describe various characteristics shared by scientists. We kept a list of their ideas on the chalkboard. As would be expected, the students came up with many popular stereotypes: geeky, no friends, pale from working all day in the lab, evil geniuses, (and my personal favorite) "tall socks and crazy hair!" We quickly broke down some of these stereotypes with help from this Tumblr: This is What A Scientist Looks Like. The students were still a bit incredulous, as many of them had never considered that scientists were anything other than white males. 

We had also put together a slide show of "A Day in the Life." I literally took a camera to work and documented my day down to the minute. Some of the slides were serious--photographs of me preparing a reaction in a round-bottom flask, or pipetting compounds into a 96 well plate. Some of the photos were silly--giving bunny ears to an unsuspecting lab tech or pretending to sword fight with paper towel tubes after lunch. Mostly we tried to show activities like attending seminar with classmates, performing an experiment, or eating lunch with my friends--all of the types of things they do in school. At the end of the slide show, we also had some photos from activities I enjoy outside of the lab: hiking in the Grand Tetons; playing rugby; swing dancing. My partner and I also took the time to emphasize that neither one of us got "the best" grades in science classes--but that we stuck with it because it was something we enjoyed.  

For many of the students, this slide show and our admission of average grades was a revelation. The discussion we had at the end of our lesson was rowdy! They talked excitedly about different types of science fields, frequently interrupting each other to ask my partner or I questions about our hobbies or the classes we took in high school to prepare to study science. More importantly in my book, they no longer saw science as an unattainable career path pursued only by socially-awkward white men. 

This spring, I am involved in SEP's STAT program, which stands for "Scientist-Teacher Action Teams." I was paired with a 4th-grade classroom along with another student who is in UCSF's Neuroscience grad program. I will save the details of our lessons for another time because this post is already too long. But needless to say, I am excited to be back in the classroom and excited to expose elementary schoolers to the joys of science.


Getting Involved in the Bay Area:
1) UCSF Science and Health Education Partnership
2) Bay Area Science Festival
3) UCB Lawrence Hall of Science
4) Community Resources for Science

Carbon Dioxide (Or, conversations with your roommate's BF)

After dinner last night, my roommate, her boyfriend, and myself were sitting around the kitchen--drinking tea and procrastinating on the dishes. I'm uncertain how we reached the topic, but a question was posed to my roommate (also a scientist) and myself:

"Why do we call Dry Ice "Dry Ice?" It's not actually water."

Now, I'm sure many people have seen dry ice, either in Halloween fog machines, or in a special freezer at the grocery store. For those who haven't seen it, dry ice is the solid form of carbon dioxide (CO2). The same gas that you exhale, and that gives soda its fizzy taste, also makes an extremely useful coolant in the solid form. "Dry Ice"as it is so called, is dry because it does not melt and leave a puddle. Instead, it converts directly to carbon dioxide gas. To understand this, we need to talk about phase changes. 

A phase change is the process by which a state of matter is altered. We talk about solids melting, like ice cream on a hot day. Or vapor condensing to liquid, like dew onto grass in the evenings. To illustrate my point further, I'm going to use two examples: water and carbon dioxide. Let's start by looking at the different phases of water--which people are generally more familiar. 

Figure 1: Phase diagram of water (1).

For water, we are accustomed to seeing three different phases. The solid form (ice), liquid (water) and  gas (steam). At 1 atm (for non-scientists, this is approximately the pressure at sea level), water exists as a solid below 273K (0ºC) and as a gas above 373K (100ºC) (2). As we change pressures or temperatures, different phases are favored. One special point on the graph above is called the triple point--this is the temperature and pressure at which we observe all three phases at once. For water, the triple point is 273.2K and 0.61 atm. 

Now let's consider dry ice. 

Figure 2: Phase diagram of carbon dioxide (3). The scale on this y axis is in bar (1 bar ~ 1 atm). 

For carbon dioxide, at normal sea level pressure, we commonly observe two phases: the solid (dry ice) at temperatures below 195K (-78ºC) and the gas (carbon dioxide gas, CO2) at temperatures above that value. In other words--at normal, everyday pressures and temperatures, dry ice sublimes. It skips the liquid phase, instead transitioning directly from the solid phase to the gas phase. It is the lower temperature of the solid, combined with the fact that there is no residue to clean up, that makes dry ice an effective coolant. And the triple point? The place where we observe all three? This point exists at -56.4ºC, and 5.13 atm. We will never see liquid carbon dioxide at room temperature, unless it is under exceptional circumstances (4).

Phase changes are important in chemistry, where we often exploit them to drive reactions in a favorable direction. But they are also important in geology and biology. Though I've touched on it only briefly here, the unique phase diagram we see in water is perhaps one of the reasons life even exists on this planet. 

References:

1. http://www.kmacgill.com/documents/phase-diagram.gif

2. An over-simplification, true.

3. Wikipedia entry on "Dry Ice." Accessed April 8th, 2013. 

4. Hanson and Green. Introduction to Molecular Thermodynamics. Sausalito, University Science Books 2008. Chapter 12 has a experiment that will allow you to observe liquid carbon dioxide. Note: a blast shield and appropriate safety gear is required!