Storylines for Mechanics

In modeling instruction, practitioners talk about the “storyline” that we present. This morning I woke up and decided to attempt “stories” for AP1/CM (using the sequence from the AP1 Course and Exam Description). I tried to write them “student-friendly” without a lot of jargon, but of course some creeped in. Let me know what you think.

Unit 1: Kinematics

When we look carefully at the positions of objects moving in one dimension at equally-spaced moments in time, patterns emerge (two models: constant velocity and constant acceleration). We describe the patterns with different representations: words, graphs, equations (derived from the graphs), and other diagrams (motion maps or dot diagrams).

Unit 2: Dynamics

Now we turn from observing the two patterns/models to trying to explain their origins. We observe that objects interact with each other in several different ways. We model the effect of the interactions on an object as forces and observe that an object will maintain constant velocity with no net force exerted on it. When a constant net force is exerted, we observe constant acceleration motion. Since we have new ideas, new representations are needed (free-body diagrams, new mathematical representations, Newton’s Laws, the concept of systems). 

Unit 3: Circular Motion and Gravitation

We extend the ideas from Dynamics (that interactions between objects may cause changes to the motion of an object or objects) to a third pattern, an object that moves in a circular path. We begin with an object moving at constant speed in a circular path due to a contact interaction(s), and then extend to objects that remain in a circular path solely due to a non-contact interaction (gravitation).

Unit 4: Energy

In Unit 2 we noticed that systems can change internally due to interactions within, or they can change due to external interactions. In this unit we go back to that idea and develop tools for comparing the initial state (“before”) to the final state (“after”) of an object or system. First we develop new quantities by examining how changes in the initial conditions of the system result in changes to the final state of a system. This leads to a very important principle: some quantities that can be calculated will remain the same total amount in the initial state as the final state, no matter how much change occurs within the system. Whenever this principle appears to be violated, we find that if we look carefully enough, we can see that it is actually correct. We keep our focus (relatively) narrow: the lens that we use in this unit is what happens when forces are exerted through a displacement. We examine many different systems, thinking qualitatively and quantitatively about their internal interactions and their interactions with external objects. More new representations result (new quantities, mathematical representations/equations, graphical representations (bar charts), and perhaps others).

Unit 5: Momentum

We begin by examining the quantity of motion that an object possesses. That quantity can be transferred to another object, and always maintains the same total amount, no matter what happens in the interaction. Again, we uncover an important principle about a different physical quantity that always remains the same and develop new representations. In Unit 4 we were concerned with the effect of interactions over a distance or displacement. In this unit we extend the observations about “quantity of motion” to examine changes to the initial and final state of a system or object with respect to the amount of time an interaction occurs. 

Unit 6: Simple Harmonic Motion

We go back to observing motion, and note that some systems that have a particular back-and-forth quality to their motion (called simple harmonic motion) all share a unique aspect: a net force that is directed towards an equilibrium position and is proportional to the displacement of an object from the equilibrium position. We apply familiar techniques to the systems as well as develop new representations/models.

Unit 7: Rotation

We apply all the previous representations and models from linear (1-d) motion to objects/systems that change their angular position with respect to a coordinate axis. 

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Changes to AP Physics 1/2 Postponed!

John Pinizzotto, one of the two Directors of AP Physics at the College Board, sponsored a reception at the AP Reading in June. He did a Q and A session during the reception. He said that he and Amy Johnson, the other AP Physics Director, have asked that the revision/realignment of the AP Physics courses (1/2, CM/CE) be pushed back a year, from 2023-2024 (first exam in 2024) to the 2024-2025 (first exam in 2025) school year. This change, he said, is to be sure that all of the materials that they can make available (AP Classroom, etc.) are completed and edited in time. This will be officially announced in the fall, assuming the higher-ups at College Board approve the change. John seemed very certain that the date will be pushed back, and offered no hedge words.

If I hear more from CB I will revise this.

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Pros and Cons of AP Classroom


  • Everything* in there has been checked for alignment with the course Learning Objectives (LOs) and Science Practices (SPs).
  • Everything* in there has been checked for accuracy.
  • Lots of Question Bank Items, including released actual questions and new questions recently written
  • There is an official solution/scoring guideline for all question items.
  • Flexibility in usage, due now or later, available in a window of time or always, paper or online (for Question Bank items)
  • Lots of Formative Assessment – i.e. Topic Questions and Personal Progress Checks (PPCs) (see this blog post for definitions), PPCs give you data about student preparedness
  • Search by LO, SP, Unit, question type, stimulus type (graph, diagram, etc.), security, exam alignment, etc.
  • AP Daily Videos can teach your students (or YOU!) essential skills – especially seems useful when you or students are struggling with a derivation in AP Physics
  • Automated grading of Multiple Choice (MCQs)
  • Scoring Guideline and online scoring of Free Response (FRQs) works pretty well
  • Students can grade their own FRQs using the same rubric teachers use
  • Can send students feedback notes (encouragement!) when grading
  • AP Daily Videos provide scaffolding for struggling students, supports inclusion of ALL students in your classroom


  • the asterisk (*) above means some mistakes were made in alignment and in accuracy, and the College Board has been excruciatingly slow in correcting them (it’s been three years, and no changes), one notable one that comes up over and over again is the Unit 1 MCQ PPC for C Electricity, it has a question that goes beyond the boundaries, AND has an incorrect solution
  • Printing Question Bank Items often involves a lot of formatting issues and there is no way to change formatting
  • Navigation in the site is sometimes confusing, although that usually improves with the frequent updates 
  • Personal Progress Checks and all Videos can only be assigned online through AP Classroom
  • Personal Progress Check MCQ sets can’t be broken into shorter chunks and many (most?) are too long for my students
  • Some PPC items seem too convoluted in their setup to be aligned with the AP Exam (they may still be useful)
  • Students must log in to see feedback and scoring, doesn’t appear to be a notification system for them  (at least I think not)
  • Videos track “watched” completion, but who knows if they actually watched the video
  • AP Classroom has, at times, been excruciatingly slow (updates may have improved this issue)
  • The Lockdown browser had a lot of problems at first and would crash, causing students to lose their work. This has been fixed to automatically submit their work when it crashes. I have not used it much since the fixes and can’t attest to the improvement. 

Best Practices in AP Classroom

This will need to be added to, as I collect more

  • Make all AP Daily Videos available at the start of the year, watch a few in class at the beginning of the year to show them how great they are, stop them at various points to discuss/answer questions. Make sure students are reminded/encouraged to watch them throughout the year. 
  • Make PPCs available, sometimes do them in class, so you can answer questions/talk about the tricky questions with everybody at the same time. This also encourages completion. Con is it takes a lot of class time.
  • Use AP Daily to teach YOURSELF tricky things and then show that tricky derivation to students yourself, in class.
  • Use PPCs for yourself BEFORE teaching a unit, to get an idea of the content, rigor level, and types of things the CB could ask (but bear in mind alignment and accuracy is not perfect for all PPCs).
  • Use AP Faculty Lectures (the longer videos) for review. Some fellow teachers have shared questions to go with those. 
  • Assign students Topic Questions in class for a warm up/bell ringer or Exit Ticket.
  • Use the Question bank to construct a quiz, test, or homework assignment (best to give students AP level work throughout the year, while scaffolding/supporting as much as possible)
  • Give a Mock Exam online using the Practice Exams (but be aware of restrictions)
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A plug for Schrodinger’s Class

Quantum Mechanics is endlessly fascinating and confusing. Famously, its implications even troubled Einstein, who helped create it! Last spring I attended a really fascinating (and at times confusing) fully online workshop called Schrodinger’s Class, from the University of Waterloo’s Institute for Quantum Computing. There were lectures by a very talented instructor and breakout room discussion sessions with teachers from all over the world. The content was basic Quantum Mechanics, but with some unusual examples, particularly around explanations of quantum computing and quantum cryptography.

They sent me a small set of demonstration materials (some cool lasers, diffraction gratings, and a few other odds and ends). All of the materials used in the class were shared in a form intended for use in the high school class. The workshop and resources were free. They are running the online version twice this year. Hey, it was so good I may attend a second time! Again here is a tinyurl, just in case:

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Marc Reif 2022 APSI Summer Presentation Schedule

AP Physics C Mechanics, Online Week 1 June 21-24, 2022 (Hosted by Walton High School)

AP Physics C Mechanics, Online Week 2 June 27-June 30, 2022 (Hosted by Walton High School)

AP Physics 2, In-person, July 11-15, 2022, at Texas Christian University, Fort Worth, Texas

AP Physics 1 for New Teachers Online, July 18-22, 2022 (Hosted by Rice University)

AP Physics 1, In-person, July 26-29, 2022, at the University of Arkansas-Little Rock, Little Rock, Arkansas

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AP Classroom (selected) Vocabulary

Some basics for those new to the College Board’s Question and Resource Database for AP students and teachers. Possibly easier than reading through the College Board’s FAQs. Please notify me of any errors or omissions.

Publicly Available

These have been released to the public. They may (possibly) be found posted on the College Board’s AP Central website. You may use these questions in print or online. You do not need to use the lockdown browser. 

Teacher Use Only 

Questions that are included in the AP Classroom database but are not otherwise available. 

Topic Question

Formative questions that are intended for you to use without a grade for accuracy. You may assign a completion grade. The light bulb ( ) symbol shows a topic question. There are supposed to be at least three for each topic. Many are marked “Teacher Use Only” , a few are “Publicly Available.” You may use these questions in print or online. You do not need to use the lockdown browser. 

Secure Questions

Questions marked by the blue shield (). Most (all?) of these came from the International Practice Exams (IPE*). These are “real” AP exams that non-US students took for the purpose of earning college credit. The Secure questions are restricted. For in-person use, students should only use the questions and the solutions in the presence of the teacher. The students may not take pictures or copies of the questions or the solutions out of the classroom. Collect work on paper and scratch paper after use. For online use, these could be assigned with the College Board’s Lockdown Browser. Students should not be taking screenshots or in other ways saving images of the problems or answers.  (*=The IPE is a different exam from the Operational Exam that most US students take every year. The Operational Exam is the source of the released Free Response questions every year.) Fall 2021 – College Board no longer requires the Lockdown Browser! See below:

Personal Progress Check

Blocks of MCQs or FRQs for formative assessment. These have been written for all units. You may use them in print (FRQs only, MCQs don’t print) or online without the lockdown browser, but you are not allowed to separate them, they must be used whole. These are also Formative questions that are intended for you to use without a grade for accuracy.

AP Daily

Instructional videos by expert AP teachers on every(?) topic and skill in the course. Each is relatively brief, typically less than eight minutes long. You can assign them and see how much your students have viewed. Also useful for teachers to see how other AP teachers present a topic. 

Faculty Lecture

Longer videos (~40 minutes) by college professors, giving an overview of an entire unit. Accessible under the “Course-level Resource” tab. Check this out: The second one for APC Mechanics was given by Brian Greene, string theorist who wrote “The Elegant Universe” and starred in the TV miniseries of the same name.  

General Note about use of College Board materials. (not vocabulary)

The College Board does not allow you to post their materials on an open website or electronically mass distribute them. It is okay for you to use them with your own students on paper or electronically (preferably behind a password-protected Learning Management System). If you want to distribute publicly available materials more widely than your own classroom, you may share with people the link to where they are found on the College Board’s own website. 

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From 2-stage to Second Chance Exams

Most of my students in AP Physics 1 struggle with unit tests for a good part of the year. There are lots of reasons for this, including a lack of previous experience with physics, the difficulty of the material, and the difficulty of the tests. I do attempt to make each unit test model a mini version of the AP Exam. When a student does poorly on one of these exams, they often panic. Many are students who are used to making As in everything. They have usually done very well on tests. They don’t really have a recovery strategy when they bomb a test.  This year is no different, and perhaps a bit worse due to virtual/hybrid instruction and a reduced class time. I have a lot of students struggling with tests. 

To help out those students who bomb a test, I came up with “Second Chance Exams,” inspired by my previous experimentation during face-to-face instruction with “2-Stage Exams.” I learned about 2-stage exams from this article by Carl Weiman (Nobel Prize winner in Physics (and founder of the PhET Sims site) and others:

Physics Exams that Promote Collaborative Learning”

The article was published in The Physics Teacher. If you teach physics and you haven’t joined the American Association of Physics Teachers, go ahead and join today

Here is my own summary of how I implemented the original approach. First you write your unit test, the “Stage 1 Exam.”. Mine are usually 10 multiple choice questions and then one or a couple of free-response questions. The source of the questions is usually old AP Physics B questions modified to be more like AP Physics 1 (make them more conceptual than calculation). I also use questions I wrote myself from scratch, and a few questions modified from other sources to be AP1-like material. The grades are scaled so that they approximate the distribution of points that corresponds to an AP Exam score. Even with the scaling, some students make a panic-inducing score.

I construct a “Stage 2 Exam” by taking some of the most-missed questions from the original test and rewriting them. If they were already conceptual questions, I change them into slightly different questions. If they were mathematical questions, I typically modify them to be more conceptual. In both cases, I focus on the mistakes in understanding that students typically make on the Stage 1 questions. 

Students take Stage 1, individually, in a typical manner (paper and pencil in my classroom, in a normal year). Then, immediately after they all finish (45 minutes to an hour into a 90 minute block), I pass out Stage 2, and students work together in their lab groups to complete that assignment as a group activity. Because of time limitations, I usually actually did Stage 2 at the next class period, although that is not the approach recommended in the original article above. 

This 2-stage approach works well for building student understanding, and improves grades. The Exam score is 75% Stage 1 (individual score), 25% Stage 2 (group score).  

In the current year, teaching Hybrid model, I came up with a different approach. Class time is greatly reduced. Many of my AP students are hybrid or full virtual and small-group collaboration is more difficult. I write and score the Stage 1 version of the exam in the same way, but I have been administering it online, using Canvas. For the second stage, I did something similar to what I describe above. I wrote a largely conceptual second stage as a Google Doc. I distributed it to the students who made a score of less than 80% on the first exam via Google Classroom. Students have to answer all of the questions to my satisfaction on the Google Doc to earn a replacement score of 80% on the Stage 1 test. Once they submit their work, I comment on what they wrote and return it to them. I only enter a grade if they complete the whole assignment to my satisfaction. Otherwise the Stage 1 Test Score remains the same. Students are allowed to work with a partner(s), look things up, or ask me questions. I do have lots of conferences (face-to-face and via Zoom) with students who submitted Stage 2, but still are stuck on some of the questions. Of course, some students ignore the whole process and just let their test scores remain low. Despite that, the system does seem to be working. It relieves a lot of the panic. I can focus students on their errors of understanding. They are encouraged to reach out directly to me when they don’t understand a second (or even a third) time. And the Stage 2 tests are relatively easy to grade. 

Here is part of a “Stage 1” Free Response question (modified from an old AP Physics B exam question):

And here is the “Stage 2” version: (I just noticed I did go ahead and ask the same question twice, probably because I saw so many calculation errors on what was supposed to be a review question)`

Here is an original Stage 1 question that was conceptual

And below is a Stage 2 version of the same question:

Here is a summary of my online version changes from Weiman Model:

Reif 2nd Chance versionOriginal Weiman 2-Stage
Optional, by invitation (test score <80%)Whole-class activity
AsynchronousDuring class, immediately after exam
Students worked individually or with partnerSmall group activity
Successful completion raised grade to 80%Exam score combination of 75% Stage 1 Score and 25% Stage 2 Score

My 2020 Online version is really a kind of modified test corrections. It seems to me to have advantages over test corrections:

1. The questions are new, so students can’t just ask somebody who got it right the first time. 

2. I can focus the questions on what the students didn’t understand, based on what they wrote on the first test.

3. The Stage 2 Tests are much easier and quicker to grade than test corrections. Everybody is answering the same questions. Everybody’s assignment is the same length. I can write an assignment of the length I want to grade, rather than grading everything that the student needed to correct. 

Let me know what you think! Stay safe!

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updated – Marc Reif 2021 APSI Presentation Schedule

note: All registration is through the College Board CVent system. Use the calendar found here or click on the links below.

If clicking a link takes you only to generic information, contact me, or try one of the other links to a same-subject workshop to find a course descrition.

AP Physics C Mechanics/Electricity and Magnetism- Combined. ONLINE

14 June to 17 June (Monday-Thursday) CDT ~ hosted by Lincoln Public Schools, Lincoln, Nebraska

AP Physics C Mechanics-Only ONLINE

22 June to 25 June (Tuesday-Friday) EDT ~ hosted by Walton High School, Marietta, Georgia

AP Physics C Mechanics/Electricity and MagnetismCombined ONLINE

28 June to July 1 (Monday-Thursday) EDT ~ hosted by Walton High School, Marietta, Georgia

AP Physics 2 (ONLINE)

12 July to 16 July (Monday-Friday) CDT ~ hosted Texas Christian University, Fort Worth, Texas

AP Physics C Mechanics/Electricity and MagnetismCombined (ONLINE)

19 July to 23 July (Monday-Friday) CDT ~ hosted by University of Arkansas, Fayetteville, Arkansas

AP Physics 1 for New Teachers ONLINE

26 July to 30 July (Monday-Friday) CDT ~ hosted by Rice University, Houston, Texas

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Peer Instruction Online Update

I really like Eric Mazur’s Peer Instruction technique. You can read about how I have used it in a face-to-face environment here:

Original Peer Instruction Blog Post

This instructional technique increases student engagement (they ask if they have a question for the day when they come in!), allows them to practice their argumentation skills (Science Practice 6, Argumentation), and can increase understanding of the basic concepts. 

The basic sequence is 

1. Project an interesting multiple choice conceptual (or maybe semi-quantitative) question

2. Students answer individually (no discussion) and anonymously

3. Students view a graph of the class’s responses

4. Students discuss with each other how they responded and why. They try to reach consensus with their discussion partners.

5. Students answer the same question again.

6. The class views the responses and the teacher leads a consensus-building discussion

The way I have used it, Peer Instruction depends on students discussing face-to-face, but how do you do that with a hybrid or online environment?

One short answer is that you can do this with This is an add-on to Google Slides. It allows you to add many types of questions to a Google Slide. The students join a Pear Deck session, view the question, and enter their responses. You can then show the graph of student responses from Pear Deck, and go through the sequence above. You need to have made a slide show with the same multiple choice question in it twice. Here is an example of a Pear Deck Slide show for a Paul Hewitt Next-Time Question.

If you don’t want to use Pear Deck, or you want to try and get the effect of Peer Instruction asynchronously, I did read about a way to use Peer Instruction online without live interaction. In The Physics Teacher journal online, I read this article, Peer Tutoring in Web-based Concept Tests. The authors used LON-CAPA to collect student justifications along with their responses. Instead of interacting live, the students can view other’s justifications.

A modification of this involves providing simulated interactions. You would present the multiple choice question, have students answer, then have them view student statements about the question and the choices. Then, after the simulated interaction, they vote again. 

Here is the Paul Hewitt Next-time question that is embedded in the “Original Peer Instruction Blog Post” referenced above:

Below are a few “student” statements I wrote to go with the question, based on my memory of how this discussion typically goes.

“The scale reads zero, because the forces on the string from each side are in opposite directions and cancel out.”

“The scale reads 100 N because the string has to hold up the 100 N weight on each side.”

“I know the objects are at rest, but it seems like each object has an effect on the scale, so I guess 200 N.”

“The scale reads 200 N because the string has to hold up two 100 N objects.

“If the scale read 200 N, wouldn’t that mean that a 100 N weight was flying upwards?”

“The scale can’t read zero because we know if you touch the string there is tension in it, right?”

Please share thoughts on using Peer Instruction in the Virtual/Hybrid Classroom in the comments.

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Covid-19 AP Physics Writing “Workshop”

Science teachers want students to think like scientists, write like scientists, and investigate like scientists. Writing has special prominence in AP Physics 1 and 2.

In order to learn to write like a scientist, students have to practice writing, get feedback, respond to the feedback, and revise their writing. Using an LMS and a few simple guiding principles can make that writing-feedback-revising cycle work in the classroom.

The Covid-19 Pandemic has caused a lot of changes in the lives of teenagers and their teachers this spring. School for us closed on March 12, and we went to online instruction through Google Classroom and Zoom meetings. The College Board elected to make all AP Exams online, 45 minute exams. The AP Physics Exams this year consisted of only two free-response questions. The questions could be answered completely by typing. None of the questions required drawings, diagrams, graphing, or derivations. In previous years, all of these tasks were very important parts of the AP exams. I spent a lot of time last year training my students to do them. Now, they were going to write about the tasks, and they were free to use notes, textbooks, or Google to help them answer the questions.

So, I changed the way I wrote my assignments. I turned drawing free-body diagrams into “describe the forces” and “calculate” into “does this equation make sense”? And I changed the way I assessed assignments. I instituted a new grading scheme. I commented on every part of every assignment. Relatively flawless work earned a 100%. Students whose work had major flaws were allowed to revise and resubmit multiple times. If a student didn’t get the work up to my standards, they earned a 60%.

This system worked very well. Rather than checking for right answers, I was looking for correct understanding. Instead of getting a grade, students were getting feedback and felt compelled to respond to the feedback. It sometimes took a couple of tries for the student to get it right, but they did improve.

So, I came up with some guidelines that worked for this grading scheme:

  • Make short writing assignments, 10 questions or fewer. One page is ideal (no scrolling).
  • Assignments involve explaining a physics idea or ideas in words.
  • Make all the assignments in an easy to grade format in Google docs.
  • Give directions to the students for their response “Type your coherent, paragraph-length response in this box”.
  • Use your judgment as to whether the answer is good enough. Make a rubric or scoring guideline before grading, to make sure that you are consistently grading.
  • If a student misstates, misinterprets, or doesn’t use one of the ideas in a correct response, they must correct their answer
  • Give students low grades (60%) and demand corrections before improving the grade.
  • Write comments on each response to show them how to correct.
  • If the corrections are not correct, write a more directed comment and ask them to redo. If there are lots of mistakes on a longer document, pick only the most important questions and only demand that they redo those.
  • Grade fast so they can work on their modified response right away.

Here is an example of an assignment I wrote. Students learned this topic virtually. Below is the stem and the stimulus for part (a).

And here is the stimulus for part (b).

Below is a student’s modified answer to part (a) with my original comment. The blue check mark means that the comment was marked as resolved. The first attempt earned a grade of 60:

And below is the same students modified answer to part (b) with my original comment:

And here are the general comments between student and teacher.

Yes, the Google Classroom Learning Management System (LMS) makes this easier, but it could be done without it, using Microsoft Word’s reviewing features, for example.

The assignments were short, students knew they had the opportunity to revise and the feedback was (relatively) swift. A number of them seemed to improve in their writing as we went through the process of reviewing for the AP1 exam.

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