Monthly Archives: December 2010

Teaching Energy

For the last couple of years, I’ve approach teaching energy from a conservation of energy perspective, deemphasized work, and focused on energy storage modes and transfer mechanisms. I think this has been very helpful for students, at least compared to starting with work and the work-energy theorem like I used to do. They understand the analogy as I pour water from the gravitational potential energy beaker into the kinetic energy beaker as the cart rolls down ramp. Students seem to more readily appreciate the idea that energy is always conserved, and, if a system doesn’t have as much energy as it used to have, we simply need to find to where it was transferred. It’s like a mystery.

This year, I’m trying to leverage as much of the modeling methodology as I possibly can which includes energy pie charts and bar charts. As usual, I started conceptually and avoid numbers. We drew energy pie charts for various scenarios. Here’s an example from the Modeling curriculum:


Students readily understood and easily created these visual models and seemed to appreciate that they could actually handle real-world aspects like friction. If an object was sliding across the floor, we would include the floor in our system so that the total energy in our system, and, therefore the size of the pie chart, would remain constant as energy is transferred from kinetic energy storage mode to the internal energy storage mode. No problems here.

We then moved to energy bar charts but continued to postpone introducing numbers in Joules calculated from equations. Students had little trouble with this visual representation. For the object sliding across the floor scenario, most groups continued to include the “surface” as part of their system such that the total energy in the system remained constant and no energy flowed out of their system. For a scenario where someone pushes a box up a ramp, some groups wanted to include the person in their system, but after a discussion of the complex energy transfers that occur within the human body, they decided to keep people out of the system and include energy flowing into the system.

We started having problems when we started calculating specific energies. Students continued to want to account for energy being transferred to the internal energy storage mode. So, for example, when asked to calculate “the average force exerted by a ball on a glove,” they would get stuck trying to calculate how much of the kinetic energy of the ball is transferred to the internal energy of the ball and how much is transferred out of the system by working. I felt like an idiot when my response was, “well, since we don’t have a model that can help us calculate how much energy is transferred to the internal energy of the ball and how much energy is transferred outside of the system, we’ll have to assume that all of the energy is transferred outside of the system.” The students looked at me with that expression of, “you have gotta to be kidding me; if that is the case, why have we been including internal energy all this time?”

Basically, we stopped including internal energy in our quantitative energy bar charts and always had energy be transferred out of the system. With the aid of this visual model, students would consistently solve relatively complicated roller coaster problems without making the typical common mistakes. I could honestly tell my classes, “those of you who drew the energy bar charts, solved this problem correctly, and those of you who didn’t bother, didn’t.” Despite this clear improvement over previous years, not having a clear rationale for why why we handled internal energy differently in the quantitative bar charts compared to the conceptual visual models was disappointing. I’m sure the students were confused by this.

Suggestions for next year?

Student Feedback on SBAR

As we near the end of the first semester, I have been reflecting, both on my own and with my team, on the changes that we made this semester to support our standards-based assessment and reporting (SBAR) philosophy. The adjustments that I expect to make in our honors physics class are minor since we now have three semester of SBAR under our belts. However, this is the first semester of incorporating SBAR into our regular physics classes. While we, as a team, have some ideas on adjustments to make for second semester, I wanted to capture feedback from the most important stakeholder of all, our students.

Inspired by Ms. Bethea’s survey that she administered at the start of the year, I created a survey to capture student feedback on various aspects of class: standards, grades, quizzes and exams, labs, other learning activities, and homework. Most questions permitted the typical strongly-agree to strongly-disagree responses, but a few were open-ended. All of my questions are available here. I don’t claim to have completed any sort of statistically significant scientific study, but I found responses interesting.

In the rest of this post I’ll share the responses of several of our students to the prompt “standards-based grading is …” to show their perspective. Some of these comments get me out of bed in the morning inspired; others, keep me up late at night concerned; and some, make me chuckle.

Get Me out of Bed in the Morning Comments

Standards-Based Grading Is…

a good alternative to the traditional grading system. In many of my other classes that do not use standards based grading, I feel that I do not really understand what I am learning, but rather, I am worried about my grade more than anything. The type of standards based grading utilized in physics ensures that I can focus on acctually learning new material, as I know that if I learn the material, I’ll have a good grade. Addtionally, I like the fact that we don’t keep losing points for simple “silly” mistakes, as this is where I usually lose points on, even though I usually understand the overall concept. This is why I feel that standards based grading is also a more accurate depiction of what people really know.

a great way to show learning in physics. It makes me think less about a letter grade and more about actually mastering the concepts we cover.

A great way for people to show what they know. If they did not understand the full idea, they can always go back and learn what they need to know. It also gives the students the knowledge as to what the teacher will be grading them on. It also saves the grade of a student who learns at a slower pace or looks at the curriculum at a different aspect than others.

fantastic. There’s more focus on what school should be about: comprehension of material retention. It is a wonderful new program; I believe courses should be taught with a much stronger foothold of standardized based grading.

Very helpful in increasing my grade and helping me further understand the material in class. The clear targets allow me to study specifically what I need to know, and I feel like I will better retain the information that I’ve learned this year.

A way to break down the material of a class and be assesed on individual topics.

only being able to move on when you fully understand a concept

awesome. This is the first year that I’ve had it, and I actually have A’s in both of the classes that I have that use it … . I think that this system really gives students the opportunity to show that they know the material, rather than getting points for doing homework and such.

more helpful than regular grading for most classes because you are not penalized for small non target-related mistakes.

good because you get a second chance to prove yourself, and improve, where as normal grading does not allow that.

A system that can be harsh if you don’t completely understand a concept, but forgiving if you spend the time to learn it and utilize second-tries.

Keep Me up Late at Night Comments

Standards-Based Grading Is…

a system of grading on a 4,3,2,1 / 3,2,1 system, instead of percentages, apparently that has to be used … because some people can’t handle regular grading.

detrimental to my grade. Though it places less pressure on me, I don’t feel like my grade in the class accurately reflects my understanding of the material nor the amount of work that I put into it.

Stressful and unindividual. My grade should be a reflection of my personal effort and growth.

REALLY ANNOYING, it penalizes you more then anything else because you have less points, and even if you just miss a few questions, you still get a zero for that target which has a huge impact on your overall test score instead of jsut getting a number grade which would be like an 85% or something. I hate SBG. I dont see the point of it what so ever.

Defy Classification Comments

Standards-Based Grading Is…

Another type of conspiracy, but less severe and possibly more helpful, although, it still will create a schism between those who understand, and those who don’t; however, this sort of grading measures how well someone knows the right answers rather than how well they can repeat it.

Pretty cool..i guess it could screw you over if you’re not careful…but whatever

What does this all mean? I don’t know yet. We’ll discuss some of the feedback tomorrow in class. I’ll have to reflect on all of this between semesters.

Adjustments for Second Semester

Our team of four physics teachers recently convened to reflect on the first semester of standards-based assessment and reporting in Regular Physics. While two of us have been implementing SBAR in Honors Physics, this Fall Semester was the first for Regular Physics. There are many, many aspects of how we integrated our SBAR philosophy that we found beneficial. However, the primary focus of our meeting was to address those aspects that we felt could be improved.

Assessing every standard for three consecutive weeks is not an effective use of time for most students.

Every standard would be assessed on three consecutive quizzes which would take three weeks. The first quiz would assess the standard in a more conceptual and basic manner and the second in a more advanced and comprehensive fashion. In combination, they provided a good measure of a student’s understanding. The third quiz wasn’t necessary for most students since they had already demonstrated that they understood the standard. That precious class time could be used more productively.

We decided that we would eliminate the third in-class quiz and make it an optional outside-of-class quiz. Those students who needed an additional opportunity to demonstrate their understanding may take this third quiz. The third quiz will be advanced and comprehensive since a student’s score on it replaces their score on the first two quizzes. Based on prior experience, we picked a single day every week when these third quizzes will be offered before and after school. At a bare minimum, students are required to submit corrections to the first two quizzes before they earn the opportunity to take the third quiz. Students are encouraged to pursue much more substantial learning activities before taking the third quiz.

The mapping of 1-4 to traditional percentages was problematic and inflated.

Our mapping of the 1, 2, 3, 4 indicators, which are used on almost all assessments, to traditional percentages as required by our school’s gradebook had a few issues. Students and parents were concerned that a “4″ didn’t map to a 100%. It is really hard to not focus on traditional grades when our grade book only presents traditional grades. At the other end, the traditional percentages assigned to 1s and 2s didn’t reflect that lack of understanding that they should. Personally, I found that some students who were really struggling to understand physics didn’t appreciate this fact because their grade was inflated due to the mapping (“I’m doing fine; I have a C”).

For the Spring Semester, we will map our 1, 2, 3, and 4 indicators to traditional percentages as follows: A 4 corresponds to a 100%; a 3, 85%; a 2, 65%; a 1, 50%.

Too many standards.

Despite warnings from the two of us with previous SBAR experience, we still defined too many standards for each unit. Several times, this resulted in too much class time spent assessing multiple targets that could have been effectively assessed in combination.

As we define the standards for our Spring Semester units we are trying to combine standards when possible. However, if standards are too broad, it is hard for students to clearly understand what they are expected to learn. Which leads us to the next aspect in need of improvement.

Use consistent terminology to more clearly communicate with students, parents, other teachers, and administrators.

Our school is in the process of creating a glossary of terms with common definitions to address this aspect that is in need of improvement. One especially egregious example concerns the use of the word “target.” Our school has a history of defining “target” as a student-understandable and demonstrable goal for a daily lesson. We have been using “target” as a synonym for standard which is much broader.

In the Spring Semester, we will call our standards “standards” and our daily goals “targets.” This will help, but not address the problem that a high-level standard may be too vague for students to clearly understand what they are expected to know. Next school year, I hope to associated several targets or objectives with each standard to provide a connection between specific learning goals and higher-level standards.

Most of us can’t imagine going back to teaching Regular Physics like we did last year. That alone is a great sign that we heading in the right direction. Thankfully, we were given time to reflect and adjust for the Spring Semester which now looks even more promising.

Update: Fri Dec 17 00:28:05 CST 2010:

I’ve scanned the above referenced glossary of terms, which is still a draft document.