Moving towards standards-based grading

I've been taking baby steps towards standards-based grading (SBG) for over two years, but this semester is the first time that I've really implemented the core ideas of SBG in any of my classes.

Last Fall I had (with my colleague) the opportunity to rewrite learning outcomes for our introductory astronomy course, ASTR101.  This is a general education survey of astronomy course without a laboratory. It is 3 credit hours and covers the solar system, stars, and galaxies.

Our campus assessment specialist pushed us to look at the revised Bloom's taxonomy word list to come up with descriptors for what we wanted our outcomes to be.  I really don't like how our campus uses the Bloom's taxonomy, but my opinions are a topic for another time.

After the outcomes were written and approved, I realized that I could implement them almost unchanged as standards for a real step towards SBG.

Here's what I did:

I went from 3 exams plus a final to no midterm exams, but nearly weekly quizzes. Each quiz is "scored" on a 0-5 point scale which measures the mastery of the standard being assessed. Students have optional homework assignments on MasteringAstronomy (which, by the way, is NOT optimized for SBG) but they are required to do the homework if they want to re-assess by retaking the quiz. If they want to retake the quiz for a third time, they have to visit my office for a discussion about the standard before they are allowed a third shot.  After the third try, the standard is closed.

Grades are weighted - 40% is based on a semester-long astrojournal, 35% is the SBG-style quizzes, 10% is a Just-in-Time-Teaching style reflection/reading review that students submit online, and 15% is a cumulative final.

So far, I've had a fairly positive experience with this in astronomy.  I should write down my workflow for getting all the assessments prepared and scored.  I have had some students come in for reassessments.  I am expecting to see more as the semester progresses.

What I could really use is a bit of feedback on how the standards are written.  I can't change the learning outcomes, but I can tweak the standards if appropriate.

There are some standards broken into multiple parts so I could have the option if necessary to break out into multiple assessments.  The goal was to have no more than 15-16 assessments. Here's the standards as I wrote them out:

1) Explain how astronomical objects move in the sky.

2a) Explain the cause of the seasons

2b) Explain the cause of moon phases.

2c) Explain the cause of eclipses.

3) Describe how the heliocentric model of the solar system was developed and why it was adopted over the geocentric model of the universe.

4a&b) Apply Kepler's Laws of orbital motion and Newton's Law of Universal Gravitation to objects in the universe.

5) Describe the functions of a telescope and types of telescopes and explain why some telescopes are placed on the ground and some in space.

6) Explain how astronomers use light to determine:

           a.) the luminosity of stars,

b.) temperature of stars,

c.) and size of stars,

d.) chemical composition of astronomical objects,

e.) the speed and direction of an astronomical object's motion,

7) Describe the nature of our solar system and how it was formed.

8) Explain how astronomers use the Hertzsprung-Russell diagram to study properties of stars.

9) Describe how stars are formed, evolve and die.

10) Describe the structure and size of the Milky Way galaxy.

11) Compare the Milky Way galaxy to other galaxies.

12) Explain how astronomers know that the universe is expanding and how they determine the age of the universe.