Cosmic Rays, Feedback, and Cookbook Labs
Two items of physics news caught my eye this week. Both are examples of how the construction of knowledge in our field is often a deliberate, careful one. First, the DAMPE collaboration has published "mid-term" results from their cosmic ray flux experiment. With improved resolution, they have an answer (in the affirmative) to a decade-long debate about whether there is a cusp in the cosmic ray spectrum at about 1 TeV (the critical graph is below). This suggests that either (a) our understanding of the astrophysical origin of cosmic rays is incomplete, or (b) this could be a signal of dark matter.
Second, two teams using data from LHCb have put forward strong claims for the detection of "long-lived" tetraquarks. They suggest a lifetime of 10^-13 s, which is quite persistent for these sorts of things. However, there is a strong dependence on the relevant masses, which are still uncertain: more data is needed.
This week, I've been thinking about what to do when we return marked quizzes to students. This form of feedback has great potential. The image below, from Brown et al, shows that when students are given an incentive to correct their work on a midterm (the pretest) they do significantly better on the final exam, with the effect particularly auspicious among medium- and lower-achieving students. A related paper suggests that students should experience productive struggle during the correction process (ie: correct solutions should not be available).
One of the CLASS statements asks students to agree or disagree with this statement: "I am usually able to complete an experiment without understanding the equations and physics ideas that describe the system I am investigating." Hu et al found that about 40% of students taking a first-year physics class agreed, suggesting they felt that physics labs could be done in a "cookbook" style. This suggests that lab reforms are urgently needed across the full spectrum of physics instruction.
I've sometimes wondered if a good percentage of primitive physics beliefs (what diSessa calls p-prims) are linguistic in nature, like the Sapir-Whorf hypothesis. A new paper by Ishimoto, Davenport, and Wittmann suggests that I'm wrong: physics (mis)understanding holds up between different linguistic cultures. The study is a fascinating comparison of FMCE results between US and Japanese students, and well worth a read.
Physics Today is carrying an interesting story about the discovery of the radiation belts around the Earth.
Katie Mummah posted a fascinating tweet chain about nuclear fuel.
Second, two teams using data from LHCb have put forward strong claims for the detection of "long-lived" tetraquarks. They suggest a lifetime of 10^-13 s, which is quite persistent for these sorts of things. However, there is a strong dependence on the relevant masses, which are still uncertain: more data is needed.
This week, I've been thinking about what to do when we return marked quizzes to students. This form of feedback has great potential. The image below, from Brown et al, shows that when students are given an incentive to correct their work on a midterm (the pretest) they do significantly better on the final exam, with the effect particularly auspicious among medium- and lower-achieving students. A related paper suggests that students should experience productive struggle during the correction process (ie: correct solutions should not be available).
One of the CLASS statements asks students to agree or disagree with this statement: "I am usually able to complete an experiment without understanding the equations and physics ideas that describe the system I am investigating." Hu et al found that about 40% of students taking a first-year physics class agreed, suggesting they felt that physics labs could be done in a "cookbook" style. This suggests that lab reforms are urgently needed across the full spectrum of physics instruction.
I've sometimes wondered if a good percentage of primitive physics beliefs (what diSessa calls p-prims) are linguistic in nature, like the Sapir-Whorf hypothesis. A new paper by Ishimoto, Davenport, and Wittmann suggests that I'm wrong: physics (mis)understanding holds up between different linguistic cultures. The study is a fascinating comparison of FMCE results between US and Japanese students, and well worth a read.
Physics Today is carrying an interesting story about the discovery of the radiation belts around the Earth.
Katie Mummah posted a fascinating tweet chain about nuclear fuel.
Seen on the web this week:
You can't do a running jump on a frictionless surface, from Alby Reid.
You can't do a running jump on a frictionless surface, from Alby Reid.
Brian Frank is color-coding circuit diagrams and the associated graphs.
Momma Physics has a really nice rotational motion apparatus.
Dan Burns has a cool 2D collision lab setup.
Marta Stoeckel posted a bunch of practicals.
Frank Noschese puts masses on a turntable.
Matt Blackman puts pie plates on a van de Graaff generator.
Patrick Kaplo has a rotary motion apparatus that shows liquids form a parabola when rotated (I find this really cool).
Lastly, a request: if you're working with undergrads (or ambitious high school students), encourage them to start thinking about research experiences this summer. This is especially true for students who may not be hearing this message from home, such as those whose parents didn't attend college, or underrepresented minorities. I will try to pass along such opportunities in the future; please tweet/email me if you know of any!