Sunday, September 15, 2013

Nebraska farming, 4H and technology updates

As the daughter of a Nebraska farmer turned city slicker, I watched 4H from afar during my childhood in suburban Seattle. Several of my cousins were involved in the sewing and cooking arm of the organization (yes, the girls- sexist I know) while most of my cousins (male and female) participated in raising livestock, plants, and showing their photography, among other activities. It always reminded me of a girl/boy scout organization or even Indian Princesses- organized crafts and outdoor activities designed to boost character, build the community and promote family unity.

An article in the latest Economist taught me that 4H has historical roots, ties with federal funding and an agenda tied in with the university culture in America. All of this has greatly influenced the way farming has evolved to promote genetically modified (GM) crops, farming as a capitalistic industry and a setup to supply the world's growing food demands. This is very different from the European model of preserving the traditional forces in the market and promoting farm practices which may be more humanitarian but not necessarily capitalistic.

On the surface, you would never know that 4H was founded, in part, to promote the hard sciences. The acronym stands for head, heart, hands and health (all four beginning with "H").  Current science projects with the organization involve egg incubators in classrooms (for urban kids) designed to teach them that their eggs do not originate at McDonald's. The money for these projects comes from government and public universities from gifts of federal land- this was set up during the Civil War and was designed to integrate technology into society. I'm guessing specifically farm culture since this is where the organization seems most active.

The historical origins of 4H are deeply rooted in the drive for new technology and farming practices to be integrated into the rural culture. In the late 1800s, the midwest plains were populated by pioneers - originally of all types of European descent- land was parceled out and homesteaders started their farms. All the while the goal of this distribution was to convert the farming techniques of these newcomers to new and (I'm assuming ) more efficient practices. (This makes sense when you think of the disposition of the average pioneer- already out of their comfort zone by coming to a completely different place) Congress sent representatives out to introduce new ways of planting hybrid corn or canning tomatoes, for example. When resistance from adults prevented new technology from being adopted, the 4H movement began. People were more likely to adopt, for example, hybrid corn, when they observed their children's 4H hybrid corn growing taller and healthier than their own.

All of this history has influenced the overall differences in how Americans view agriculture as opposed to how Europeans view it. In America, agriculture is a commodity- a capitalistic business designed to reap the highest profit possible. This is not the case in Europe where more traditional methods are used, often at the expense of turning the maximum profit or even keeping up with demand.

I had no idea my cousins' childhood pastime had such historical roots and educational goals.

Tuesday, July 30, 2013

Improved Test Scores: Why and How

Standard Learning Objective Quiz Results for Introductory Chemistry

Fall 2012 Results

2/19 students got 8/8

5/19 students got 7/8

3/19 students got 6/8

6/19 students got 5/8

2/19 students got 4/8

1/19 students got 3/8

Spring 2013 Results (after implementation of online homework system)

4/21 students got 8/8 

5/21 students got 7/8

4/21 students got 6/8

5/21 students got 5/8

3/21 students got 4/8

These scores are, I believe, proof that an effective online homework system can make an overall difference in student comprehension. Especially in a discipline like chemistry, it is so easy to complete a homework assignment and not understand what overall concepts were reinforced by that assignment. An online homework system can give students the chance to complete an assignment, receive tutorial help with the assignment and real-time feedback on the accuracy of their answers. Then later they can go back and redo the problem for review (practice for the final exam).

As you can see from my small sample size, more students in my class scored 6,7,8 (out of 8) after the implementation of an online learning homework system.

Tuesday, July 02, 2013

Transforming Matter: A History of Chemistry from Alchemy to the Buckyball (Johns Hopkins Introductory Studies in the History of Science)

This is the book I pulled off of last year and designated as my project for the year. This book and about ten other books of varying subjects. No, I haven't finished it yet but I'm close. My goal is to review it for this blog. Between hosting my in-laws, preparing for baby Shamon #2 and finding a new house, life is really busy right now.

A blog entry is certainly overdue. I  hope to return soon.

Wednesday, April 03, 2013

Limiting Reactant/Reagent

3 FeO(l) + 2 Al(l) → 3 Fe(l) + Al2O3(s)

This is the best I could do for cutting and pasting a useful equation from my PowerPoint slides. The superscripts and subscripts do not carry over.

If you have 25.0 grams of each reactant, which is limiting?
How do you approach this problem?   Divide 25.0 grams by the molar mass of each reactant. (71.85 g/mole for FeO and 26.98 g/mole for Al). This gives you moles of each reactant. You cannot compare grams to grams (as given in this case) because it is a nonsensical relationship in chemistry terms. You must compare moles to moles. Now, use moles of each reactant to figure out which gives the LEAST amount of product. This is where you use your balanced chemical equation to find the molar ratio of reactant to product. In this case you have 3 moles of Fe(l) for 3 moles of FeO(l). Essentially this is a 1:1 relationship. So your moles of reactant for FeO is the same as moles of product of Fe(l). For Aluminum, you have 3 moles of FeO (from the coefficient of the balanced equation) for every 2 moles of aluminum. Therefore it is a 3/2 relationship of moles of product to moles of reactant.  

Although you can compare moles of product from one reactant to moles of product from another reactant to determine the limiting reagent, many times this number is converted back into grams by multiplying by the molar mass of the product you are dealing with.  

The comparison in this case is between 19.4 grams of Fe(l) (from 25.0 grams of FeO) versus 77.6 grams of Fe(l) from 25.0 grams of Aluminum. By definition, the limiting reactant is the one that gives the least amount of product. Therefore, the Iron II oxide is the limiting reactant. The 19.4 grams of product is your maximum amount of product from these two given amounts of reactant, or in other words, it is your theoretical yield.    

Tuesday, March 26, 2013

Illustrations to differentiate ionic and covalent bonding

My students found these illustrations helpful in understanding the differences in bonding behavior of molecules vs ionic compounds. I included these on a review sheet that was previously posted without illustrations. They adamantly insisted I update the posted review sheet with these pictures!

 The Na-Cl bond is electrostatic in nature with the positively charged sodium clinging to the negatively charged chlorine. While they "cling" together, there is no overlap of their orbitals. This is in contrast to the carbon dioxide where the orbitals are totally intertwined with each other. You can see that the atoms (represented by balls) are not distinct circles but circles that are welded together to cover up part of the diameter of each. This represents the sharing of electrons in covalent bonding. 

The HF bond represents the bonding of an acid, which is technically a molecular bond as well. 

My question for the students was this: What is CaCO3? Can you tell by the picture and/or the type of elements in the compound whether it is ionic or covalent?