Tag Archives: IB Physics

2014-2015 Year In Review: IB Physics SL/HL

This was my first year teaching IB Physics. The class consisted of a small group of SL students with one HL, and we met every other day according to the block schedule. I completed the first year of the sequence with the following topics, listed in order:

    Semester 1

  1. Unit 1 - Experimental Design, Uncertainty, Vectors (Topic 1)
  2. Unit 2 - Kinematics & Projectile Motion (Topic 2.1)
  3. Unit 3 - Newton's Laws (Topic 2.2)
  4. Unit 4 - Work, Energy, and Momentum (Topic 2.3)
  5. Semester 2

  6. Unit 5 - Circular Motion, Gravitation, and Orbits (Topics 6.1, 6.2)
  7. Unit 6 - Waves and *Oscillation(Topic 4, AHL Topic 9, *AHL Engineering Option Topic B3.1,3.2)
  8. Unit 7 - Thermal Physics (Topic 3, Engineering Option Topic B2)
  9. Unit 8 - *Fluid Dynamics (Engineering Option Topic B3)

For the second semester of the course, there was at least one block every two weeks that was devoted to the HL student and the HL only content - the SL students worked on practice problems or other work they had for their IB classes during this time. Units 7 and 8 were concurrent, so the HL student had to work on both the thermodynamics content and the fluid dynamics content together. This was similar to how I did it previously while teaching the AP physics B curriculum.

One other fact that is relevant - none of my students are native speakers of English. More on this later.

What worked:

  • The growth students made during the year was significant. I saw students improve in their problem solving skills and their organization in the process of doing textbook style assessment problems.
  • I learned to be honest about the IB expectations for answering questions on assessments.In the beginning, I tried to shield students from questions that combined conceptual understanding, computation, and complex language, often choosing two out of the three of them for any one question that I either wrote or selected from a bank. My motivation was to isolate assessment of the physics content from assessment of the language. I wanted answers to these separate questions:
    1. Does the student understand how the relevant physics applies here?
    2. Does the student understand how to apply the formulas from the reference table to calculate what the question is asking for?
    3. Can the student process the text of the question into a physics context?
    4. Can the student effectively communicate an answer to the question?

    On official IB assessment items, however, this graininess doesn't exist. The students need to be able to do all of these to earn the points. When I saw a significant difference between how my students did on my assessments versus those from IB, I knew I need to change. I think I need to acknowledge that this was a good move.

  • Concise chunks of direct instruction followed by longer problem solving sessions during class worked extremely well. The students made sense of the concepts and thought about them more while they were working on problems, than when I was giving them new information or guiding them through it. That time spent stating the definitions was crucial. The students did not have a strong intuition for the concepts, and while I did student centered conceptual development of formulas and concepts whenever possible, these just didn't end up being effective. It is very possible this is due to my own inexperience with the IB expectations, and my conversations with other teachers helped a lot to refine my balance of interactivity with an IB pace.
  • Students looked forward to performing lab experiments. I was really happy with the way this group of students got into finding relationships between variables in different situations. Part of this was the strong influence I've developed with the Modeling Instruction curriculum. As always, students love collecting data and getting their hands dirty because it's much more interesting than solving problems.

What needs work:

  • My careless use of the reference sheet in teaching directly caused students to rely excessively upon it. I wrote about this previously, so check that post out for more information. In short: students used the reference sheet as a list of recipes as if they provided a straight line path to solutions to questions. It should be used as a toolbox, a reminder of what the relationships between variables are for various physics concepts. I changed this partly at the end of the year, asking students to describe to me what they wanted to look for on the sheet. If their answer was 'an equation', I interrogated further, or said you aren't about to use the reference sheet for what it was designed to do. If their answer was that they couldn't remember if pressure was directly or inversely related to temperature, I asked them what equation describes that relationship, and they were usually able to tell me.
    Both of these are examples of how the reference sheet does more harm than good in my class. I fault myself here, not the IB, to be clear.
  • The language expectations of IB out of the gate are more of an obstacle than I expected at the beginning of the year. I previously wrote about my analysis of the language on IB physics exams. There tends to be a lot of verbal description in questions. Normally innocuous words get in the way of students simultaneously learning English and understanding assessment questions, and this makes all the difference. These questions are noticably more complex in their language use than that used on AP exams, though the physics content is not, in my opinion, more difficult. This is beyond physics vocabulary and question command terms, which students handled well.
  • Learning physics in the absence of others doesn't work for most students. Even the stronger students made missteps working while alone that could have been avoided by being with other students. I modified my class to involve a lot more time working problems during class and pushed students to at least start the assigned homework problems while I was around to make the time outside of class more productive. Students typically can figure out math homework with the various resources available online, but this just isn't the case for physics at this point. It is difficult for students to get good at physics without asking questions, getting help, and seeing the work of other students as it's generated, and this was a major obstacle this semester.
  • Automaticity in physics (or any subject) shouldn't be the goal, but experience with concepts should be. My students really didn't get enough practice solving problems so that they could recognize one situation versus another. I don't want students to memorize the conditions for energy being conserved, because a memorized fact doesn't mean anything. I do want them to recognize a situation in which energy is conserved, however. I gave them a number of situations, some involving conservation, others not, and hoped to have them see the differences and, over time, develop an awareness of what makes the two situations different. This didn't happen, partly because of the previous item about working physics problems alone, but also because they were too wrapped up in the mechanics of solving individual problems to do the big pciture thinking required for that intuition. Group discussions help on this, but this process is ultimately one that will happen on the individual level due to the nature of intuition. This will take some time to figure out.
  • Students hated the formal process of writing up any parts of the labs they performed. This was in spite of what I already said about the students' positive desire to do experiments. The expressions of terror on the students' faces when I told them what I wanted them to do with the experiment break my heart. I required them to do a write-up of just one of the criteria for the internal assessment, just so they could familiarize themselves with the expectations when we get to this next year. A big part of this fear is again related to the language issue. Another part of it is just inexperience with the reality of writing about the scientific process. This is another tough egg to crack.

There was limited interest in the rising junior class for physics, so we won't be offering year one to the new class. This means that the only physics class I will have this year will be with the same group of students moving on to the second year of IB physics. One thing I will change for physics is a set of memorization standards, as mentioned in my post about standards based grading this year. Students struggled remembering quick concepts that made problem solving more difficult (e.g. "What is the relationship between kinetic energy and speed?") so I'll be holding students responsible for that in a more concrete way.

The issues that need work here are big ones, so I'll need some more time to think about what else I will do to address them.

Releasing my IB Physics & IB Mathematics Standards

Our school is in its first year of official IB DP accreditation. This happened after a year of intense preparation and a school visit last March. In preparation for this, all of us planning to teach IB courses the next year had to create a full course outline with details of how we would work through the full curriculum over the two years prior to students taking IB exams.

One of the difficulties I had in piecing together my official course outline for my IB mathematics and IB physics courses was a lack of examples. There are outlines out there, but they were either for the old version of the course (pre-2012) or from before the new style of IB visitation. The IB course documents do have a good amount of detail on what will be assessed, but not the extent to which it will be assessed. The math outline has example problems in the outline which are helpful, but this does not exist for every course objective. The physics outline also has some helpful details, but it is incomplete.

The only way I've found to fill in the missing elements is to communicate directly with other teachers with more experience and understanding of IB assessment items. While some of this has been through official channels (i.e. the OCC forums), most has been through my email and Twitter contacts. Their help has been incredible, and I appreciate it immensely.

At the end of the first semester for Mathematics SL, Mathematics HL (one combined class for both), and Physics SL/HL (currently only SL topics for the first semester), I now have the full set of standards that I've used for these courses in my standards based grading (SBG) implementation. I hope these get shared and accessed as a starting point for other teachers that might find them useful.

For my combined Mathematics SL/HL class:
Topics 1 - 2, IB Mathematics SL/HL

For my combined Physics SL/HL class:
Topics 1 - 2, IB Physics SL/HL

The third column in these spreadsheets has the heading 'IB XXXX Learning Objective' - these indicate the connection between the unit standard (e.g. Standard 3.1 is standard 1 of unit 3) to the IB Curriculum Standard (e.g. 2.3 is Topic 2, content item #3). Some of these have sub-indices that correspond with the item in the list of understandings in the IB document. IB Mathematics SL objective 1.3.2 refers to IB Topic 1, content item #3, sub-topic item #2.

If you need more guidance there, please let me know.

If you are a new IB Mathematics/Physics teacher accessing these...

...please understand that this is my first year doing the IB curriculum. There will be mistakes here. In some cases, I also know that I'll be doing things differently in the future. If these are helpful, great. If not, check the OCC forums or teacher provided resources for more materials that might be helpful.

If you are an experienced IB Mathematics/Physics teacher accessing these...

...I'd love to get your feedback given your experience. What am I missing? What do I emphasize that I shouldn't? What are the unspoken elements of the curriculum that I might not be aware of as a first year? Let me know. I'd love it if you could give me the information you wish you had (or may have had) to be maximally successful.

I've benefited quite a bit from sharing my materials and getting feedback from people around the world. I've also gotten some great help from other teachers that have shared their resources. Consider this instance of sharing to be another attempt to pay that assistance forward.

Uncertainty about Uncertainty in IB Science

I have a student that is taking both IB Physics with me and IB Chemistry with another science teacher. The first units in both courses have touched on managing uncertainty in data and calculations, so she has had the pleasure (horror) of seeing how we both handle it. For the most part, our references and procedures have been the same.

Today we worked on propagating error through the calculation \Delta x = \frac{1}{2}at^2 with uncertainties given for acceleration and time. The procedure I've been following (which follows from my experiences in college and my IB textbooks) is to determine relative error like this:

\frac{\delta x}{\Delta x} = \frac{\Delta a}{a} + 2 \cdot \frac{\Delta t}{t}

In chemistry, they are apparently multiplying uncertainty by 0.5 since it is a constant multiplying quantities with uncertainty. On a quick search, I found this site from the Columbia University physics department that seems to agree with this approach.

My student is struggling to know exactly what she should do in each case. I told her that everything I've seen from the IB resources I have in physics supports my approach. The direct application of the formula suggests that an exact number (like 1/2) has zero uncertainty, so it shouldn't be involved in the calculation of relative error. That said, the different books I've used to plan my lessons agree with each other to around 95%. There is uncertainty about uncertainty within the textbooks discussing how to manage uncertainty. Theory of knowledge teachers would love the fact that teachers of a generally objective field (such as science) have to occasionally acknowledge to our students that textbooks don't tell the entire story.

The reality is that there are a number of ways to handle uncertainty out in the world. Professionals do not always agree on the best approach - this conversation on the Physics Stack Exchange has a number of options and the mathematical basis behind them. For students that are used to having one correct answer, this is a major change in philosophy.

Thus far in my teaching career, I haven't delved this deeply into uncertainty. The AP Physics curriculum doesn't require a deep treatment of the concepts and roughly ignores significant figures as well. I talked about some of the issues with uncertainty with students, but I never felt it was necessary to get our hands really dirty with it because it wasn't being assessed. We also learned error analysis in my experimental design courses in college, and it was part of the discussion there, but it was never the class discussion. It's really interesting to think about these issues with students, but it's also really difficult.

It seems that the questions that have resulted both from class and for my own understanding are exactly the style of conflict that the IB organization hopes will result from its programs. The way this student throws her hands up in the air and asks 'so what do I do' and managing the frustration that results is the same difficulty that we as adults face in resolving daily problems that are real, and complex.

The philosophy that I shared with the students was to be aware of these issues, but not to fear them. It should be part of the conversation, but not its entirety, especially at the level of students that are new to physics. I'm confident that some of the discomfort will melt away as we do more experimentation and explore physics models that tend to describe the world with some level of accuracy. The frustration will yield to the fact that managing uncertainty is an important element of describing how our universe works.