Even the most thoughtful, dedicated teachers spend enormously more time worrying about their lectures than they do about their homework assignments, which I think is a mistake. Extended, highly focused mental processing is required to build those little proteins that make up the long-term memory. No matter what happens in the relatively brief period students spend in the classroom, there is not enough time to develop the long-term memory structures required for subject mastery.
To ensure that the necessary extended effort is made, and that it is productive, requires carefully designed homework assignments, grading policies, and feedback.
In a previous post I showed some examples of how some chemistry problems posted on Reddit and Yahoo can be solved simply by typing them into Wolfram Alpha (WA) and suggested that we should revisit the general chemistry curriculum in light of new tools WA.
To get more data I signed up for the Introduction to Chemistry MOOC offered by Coursera. In this course the homework consists of 8 quizzes, each with between 11 and 15 questions plus a Pre-Course Concept Assessment Quiz. Here's what I found.
Pre-Course Concept Assessment Quiz
7 out of 15 questions could be done by typing them into WA. For example: Solve the following system of two equations with two unknowns: x + y = 1 and 5x + y = 2. This questions tests for manual skills not really needed anymore, much like "what is the square root of 2?".
This question was much better: An architect presents a 3 inch wide by 4 inch deep by 3 inch tall model of a new central campus dorm. If the final building foundation is 126 feet wide, then how tall will the building be? Of course this can also be solved with WA but the student must reformulate the question first. I usually don't count questions such as this as square-root-of-2 problems.
Week 1 Introduction
4 out of 15 questions could be done by typing them into WA. For example: Wavelength of orange light is 0.00000060 m, scientific notation is ______ m. A conceptual question on scientific notation would be much more useful. Questions like this is also trivial in WA: A Boeing 747 carries 1.834 x 10^5 liters of jet fuel. Convert this volume to cm3. These are "wasted" questions.
4 questions concerned significant figures, which WA does not handle. For example: Perform the following calculation and input the answer expressed to the correct number of significant figures: 80720 ÷ (15.3 – 7.009) × 1.86. This is an important skill that must be taught. Even though it's not used in the rest of the course :).
Week 2 Matter and Energy
10 out of 13 questions could be done by typing them into WA. For example: Name the following compound: CaF2. Even: Which of the following neutral atoms has the smallest first ionization energy? Si, Sc, Sr, B, N. A much better question is why the order is what it is, but how to phrase that as a multiple choice question?
Here's one that WA couldn't answer: Identify each of the following ions with their correct chemical symbol: Species with 8 protons and 10 electrons; Species with 30 protons and 28 electrons.
Week 3 Chemical Composition, Solutions, and Dissolution Equations
8 out of 11 questions could be done by typing them into WA. Here I count questions like: A 12.0 g sample of HF is dissolved in water to give 3.1×102 mL of solution. The concentration of the solution is: that take a little bit of thought. But there are completely straight forward questions like: Dinitrogen monoxide (more commonly called nitrous oxide) has the chemical formula N2O. What is the mass percent oxygen in nitrous oxide?. Also, simple trial and error becomes effortless: A compound containing phosphorus and oxygen has a molar mass of 219.9 g/mol and an empirical formula of P2O3. Select its molecular formula from the following list: P6O8, P4O6, PO, none of the formulas listed are correct, P2O3
Here's one that requires some thought: A sample of sodium dichromate, Na2Cr2O7, is placed into a container by itself. The sample of material in the container is analyzed, and it is found to contain exactly 0.67 moles of sodium atoms. How many moles of oxygen atoms are in this sample?
Week 4 Chemical Composition, Solutions, Dissolution and Precipitation
1 out of 11 questions could be done by typing them into WA and it is: Determine the oxidation state of the nitrogen in each of the following molecules or ions: NO2^-1
WA is simply not yet equipped to handle questions like: A solution is known to contain only one type of anion. Addition of Tl1+ ion to the solution had no apparent effect (all ions remained in solution), but addition of Ba2+ ion resulted in a precipitate. Which anion is present? SO4^2-, Cl1-, I1-, NO3^1-
Week 5 no quiz
Week 6 Atomic Structure
5 out of 14 questions could be done by typing them into WA. For example: Use the periodic table to write the electron configuration for the following element: Ba. By itself it is a pointless question. What you really want to know is: "How many core and valence electrons are in the following neutral atom? Se" which is also readily available from WA.
And just because a question cannot be answered easily with WA doesn't mean it's a good question. For example, what's the point of this question?: Give the number of s, p, d, and f electrons in the following neutral atom when it is in the ground state.
I liked this one though:
Below is the energy level diagram (not drawn to scale) representing the transitions made by an electron in a hydrogen atom that result in the observed lines of both the absorption and emission spectra. Some are in the visible region, and some are not. 4 different energy photons are represented (approximate wavelengths are given in parentheses): infrared (~ 10-4 m), red (~ 10-6 m), blue (~ 10-7 m), ultraviolet (~ 10-8 m). Match the transition (a - h) with the photon described (approximate wavelengths are given in parentheses.) Your answer input should be a single, lower case letter. (Please note: This is not a problem for which a calculator is required. Your knowledge of the Bohr model of the atom and the relative energies of transitions is all that is needed.)Week 7 Molecular Structures and Shapes
4 out of 11 questions could be done by typing them into WA. Drawing Lewis structures is becoming a square-root-of-2 problem: Select the correct Lewis structure for the following ion. N3-. But most of the questions in this section are quite good and not immediately answerable by WA.
Week 8 Ideal Gas Law and Intermolecular Forces
2 out of 11 questions could be done by typing them into WA. For example: A container of 8.03 x 10-3 moles of hydrogen gas has a volume of 20.9 mL and a temperature of 20.8 degrees C. You could argue that this example requires some processing of the information given, but certainly all the "heavy lifting" in terms of units and conversions is done.
But, again, most of the questions in this section are quite good and not immediately answerable by WA.
Week 9 Solution Calculations
7 out of 12 questions could be done by typing them into WA. For example imagine being completely stuck on "What is the mass of fructose, also known as fruit sugar (C6H12O6), in a 127 mL sample of glucose solution that has a concentration of a 1.44 M?". Simply type in 127 mL 1.44 M fructose in WA.
Surprisingly WA can't handle "What is the mass percent concentration of the solution if 11.9 g of ethanol is dissolved in 67.4 g of water? " directly.
So, 42% (48/113) of the questions can be easily done with WA and at least a 3rd are what I would call square-root-of-2 questions - questions that are no longer really meaningful in and of themselves. And in many weeks the majority of the questions are like that. That's a waste of very valuable student time and attention.
I should mention that there are also advanced problems sets that "need to be completed in order to achieve a statement of accomplishment with distinction." Many of these are quite interesting problems that I think could be assigned to all students if they are taught to use WA effectively. This is what we should be aiming for:
1. An 8-year-old child who weighs 66 pounds needs to be treated for a novel influenza A (H1N1) infection. For a child of this size, the total daily recommended amount of the antiviral drug Oseltamivir is 4.0 mg of drug per kg of body weight. The total daily amount of medication should be divided into two equal doses. (Source: Clinical Infectious Diseases 2009; 48:1003–1032.) A liquid suspension of this medication contains 12 mg Oseltamivir per mL. How many mg of the antiviral drug should be given to the child for her first dose?
1. Look for the chemistry terms and unfamiliar words. Do you understand all of the terms?
2. What is the question asking for?
3. Write down in words a short sketch for how you would solve this problem. What are the steps to solve this problem? Is any necessary information missing? Which information is provided that you do not need to answer the question?
4. Solve Problem 1: the answer is _______ mg.
This work is licensed under a Creative Commons Attribution 4.0