The Very Spring and Root

An engineer's adventures in education (and other musings).

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January 2013

The Free Knowledge Stand: Physics at Breakfast

100_0787This January, upon return from the winter break, students were greeted with the grand opening of the Free Knowledge Stand at breakfast in the cafeteria.

My co-resident and I keep office hours after school on Tuesdays and Thursdays, which are usually well-attended. However, we noticed that many of our students who needed the most support in Physics were not showing up for additional help. At first we assumed that they maybe just didn’t want to, had other priorities, or didn’t value the subject matter or our time. But when we asked students why they weren’t showing up for extra help, we got a variety of reasons that at first we hadn’t considered: transit, work, and family.

Due to Boston’s complex busing system, many of our students are coming from very far across the city, and need to catch BPS shuttle buses to major transit stations, or risk having to make a 2 hour trek home via surface buses (which, as we know, isn’t exactly providing equitable access to underserved populations). These shuttles leave immediately after school, and there is no recourse for missing them other than making one’s own way. Additionally, we found through our case study interviews that many of our students either work after school to help support their families or have to take care of siblings while others work.

Ok, easy we thought. We’ll just come in early before school and have students come in when they get to school. However, this wasn’t as straightforward as it seemed. One hurdle we ran into was (necessary) security: students aren’t allowed to roam the halls unescorted before hours. So we would be constantly running back and forth between classroom and cafeteria.

The other hurdle was breakfast. The students were reluctant to leave the cafeteria in the morning because that is when they eat breakfast — and food is not allowed in the classrooms. If you’re getting into school at 7am after a 1.5 hour commute to school, having breakfast before is probably not an option; and if you’re on the Federal Free or Reduced program for low-income students (85% of our student body), you probably don’t have many other options for breakfast anyway. So that wasn’t budging.

The solution: The Free Knowledge Stand, a play on a commonly shouted phrase of our mentor teacher in the hallways, “Free knowledge! Free knowledge today! Come and get the knowledge! Free knowledge my friend, why are you not learning? Free Knowledge! …”

So, every morning, I send out a tweet from my teacher Twitter account letting students know when we will be there. My co-resident and I try to get in at 7am (doesn’t always happen… curse you snooze alarm), when we set up our laptops and our Free Knowledge Stand sign in the cafeteria. Most days, we’ll get a few clients. Some days, no one comes for help — on those days we just do our work of planning and BTR papers as we normally would.

And aside from the content help, the Free Knowledge has been a great way to form positive relationships with students. Many of them like to stop by with their breakfasts and just say hi, talk about what we did in class, and ask far-out questions about the material that they were wondering (“So Mister, is there like, friction everywhere? Like what about in the sun, is it you know like, too hot for friction in there?”).

Since there are two of us, we are often able to tag team, one resident directly helping students while the other does lesson planning and chiming in when able — sharing the workload. The Free Knowledge Stand has been a great way to provide extra physics help and get to know students, without really taking any additional time out of our days. And yes, it is always the grand opening — we’ve got cheesy/nerdy science teacher reputations to maintain after all.

Lesson Plan: Predictions With Conservation of Energy

by Nalin A. Ratnayake

Unit: Work and Energy, Component 2: Conservation of Energy
Date: January 15th, 2013
Day/Block: Day 4, Blocks A(3) / E(2) / F(6)
Time Available: E 58 min, A 58 min, F 65 min

Objective: You will be able to predict and analyze motion using the Law of Conservation of Energy.

Criteria for Success:

  1. Can I predict the final mechanical energy of an object in motion using energy conservation?
  2. Can I determine if and how an object’s mechanical energy has changed?
  3. Can I solve a physics problem using energy conservation?

Assessment: Handout and Exit Ticket
The handout will show qualitative understanding of Criteria for Success 1 and 2.
The short worksheet will show quantitative understanding of the Criterion for Success 3.

[10 min] Do Now

Please have a seat and work quietly on the Do Now.

A ball of mass 15.5 kg is released from rest at a point 1.2 m high.

1. If we ignore air resistance, what will be the velocity of the ball at the lowest point of motion?

2. If we assume that air resistance does -20 J of work on the ball as it falls, what will be the velocity at the lowest point of motion?

Share out. Specific questions to ask students: Can you step me through how you found the velocity? How do you know much initial mechanical energy the ball has? How do you know that the total mechanical energy will remain constant? Where does the kinetic energy of the ball come from?  What does the work done by friction do to the mechanical energy of the ball?

[2 min] Framing the Day

The scenario we will be looking at today will be very similar to the Do Now… only more dangerous!

Objective: You will be able to predict and analyze motion using the Law of Conservation of Energy.

Criteria for Success:

  1. Can I predict what will happen to the mechanical energy of an object by using energy conservation?
  2. Can I determine if and how an object’s mechanical energy has changed?
  3. Can I solve a physics problem about the motion of an object using energy conservation?

Can someone please raise his or her hand and explain what we are doing today?
Can someone please raise his or her hand and remind us how we will know if we are successful today?

[35 min] Will Professor Lewin Survive?

Note: The following activity will be outlined on a handout / graphic organizer.

We are handing out a worksheet. These will be collected today at the end of the period. Please take a couple of minutes to read the first two sections, labeled “Video” and “Directions”.

Professor Walter Lewin is going to put his life on the line to prove the law of the conservation of energy. He will release a 15.5 kg pendulum bob from his chin, and wait to see what happens when the ball swings back at his face! Will the ball smash his face in? Or will the laws of physics protect him? We will find out….
Can someone please raise their hand to volunteer to read the first paragraph for us?


  • We will be watching a video that goes along with this handout. Do not move ahead. Some questions we will do as a class, some as a table, and others individually.
  • Write your answers in complete sentences wherever possible. This helps organize your thinking and gives you better study materials later for quizzes and tests.

Can someone please raise their hand and tell us, what is one direction we should follow today? Why should we do that?
Can someone please raise their hand and tell us, what is another direction we should follow today? Why should we do that?

Play the video of Walter Lewin putting his life on the line to prove Conservation of Energy.

Stop the video at 2:54.  (Right after “…this will be my last lecture.”)


Answer question 1 individually on your worksheet now.
1. What kind(s) of mechanical energy does the ball have right now and how do you know?
Quick share, check for agreement or disagreement and why.

Take a couple of minutes to work with your table group on the first column of the table (question 2).
After each column, ask a student to share out what their group answered. Questions to ask: Why do you think that the mechanical energy will increase/decrease? Why will this make the height higher/lower? What does positive/negative work do to the mechanical energy of the pendulum? How will we know if the mechanical energy is higher/lower?

Repeat for questions 3 and 4.

2. Prof. Lewin does not push the ball and we assume no air resistance 3. Prof. Lewin does not push the ball but we include air resistance 4. Prof. Lewin accidentally pushes the ball as he lets go
What kind of work will be done on the ball (positive / negative / none)?
What will happen to the total mechanical energy of the ball (increase / decrease / constant)?
What will be the height of the ball when it swings back to Prof. Lewin (higher / lower / same)?
Will Professor Lewin be safe (yes / no)?

Add this diagram to the slide to be clear about what I mean by “height”:

Answer question 5 on your worksheet individually.
5. Make your prediction: What will happen to the mechanical energy of the ball? How will you know if your prediction is right or wrong?

Play the rest of the video.

Show a side by side of the before (at the time of release) and after (1 cycle):

Ask the class:
I was careful to stop the video exactly when the ball reached its maximum height on the return swing. Is he at the same position or not? What do you notice about the ball’s position?

At this point there should be at least 20 min remaining in the period.

Answer the following question individually:
6. What happened to the mechanical energy of the ball, and how do you know?  What evidence tells you so?

Possible questions:What happened to the mechanical energy of the ball, and what evidence do you have? Was there work done on the ball? If so, by what force and was it positive or negative work? How can we explain what happened using the Law of Conservation of Energy? As students answer, ask for agreement or disagreement and why.

In a couple of minutes, I’m going to ask you to answer question 7 individually. But before we do that. you have 2 minutes to check with your partner and make sure you agree on what happened. This is your only chance to confer before answering question 7 on your own.

Now, answer question 7  on your own.
7. Write out a short story of what happened to Prof. Lewin’s swinging pendulum. You must answer the following questions in your story: Was work done on the ball and by what force?  What did this work do to the mechanical energy of the ball? What did we observe that told us what happened to the mechanical energy of the ball?

[5 min] Exit Ticket

Professor Lewin released a 15.5 kg pendulum from 1.20 m high. We carefully measure the height of the ball when it swings back towards him, and determine that the ball only went 1.05 m high when it came back. How much work was done by air resistance on the ball?

Collect student work. If running out of time, ask co resident to help photograph worksheets and exit tickets of case study students as a worst case fallback option.

52 min total:  ~5 min of buffer
If need be, the CONFER section of the plan can be eliminated without impact to the cognitive demand or student sense-making in the lesson.

BTR: Lasting the Winter

My latest blog for BTR, Lasting the Winter, posted a couple of days ago. Here’s the takeaway:

The Dalai Lama reminds us that “it is under the greatest adversity that there exists the greatest potential for doing good, both for oneself and others.” So despite this dark, cold time in the residency, I have to believe that it will make us stronger—that it has made our love stronger. Though I’m sure most of us would be friends anyway under different circumstances, the very fact that we surely must pull together for each other, or all be that much more miserable, certainly should add both urgency and potency to the acts of kindness we reserve for our fellow residents. For, by extension, we cannot help but serve our common purpose thereby as well.

You can read the full post on the BTR program blog.

Lesson Plan: Conservation of Energy using a Music Video

Lesson 2.2: Exploring Conservation of Energy

Unit: Work and Energy, Component 2 – Conservation of Energy
Date: January 10th, 2013
Day/Block: Day 1 –  A/E/F
Time Available: A 58min / E 48min / F 65min

You will be able to design and analyze a Rube Goldberg Machine using the Law of Conservation of Energy.

Criteria for Success:
Can I design my own machine that transfers mechanical energy between objects through work?

Can I use the Law of Conservation of Energy to explain how my design transfers energy?

Handout with machine design and analysis questions.


[10 min] DoNow:

The complicated chain of events in the music video is called a “Rube Goldberg Machine”. These machines use many transfers of energy between a whole lot of objects in order to do a very simple task.

Invent your own small (2 objects) Rube Goldberg machine. How would you use one object to make another object do something else? Where is there work and energy? How does one object transfer energy to another?


[10 min] Discussion: Music Video

Show OK Go’s music video for “This Too Shall Pass”: (4 min)

Note: Watching the video was assigned as homework the previous night, along with the following guided questions: Where do you see work? Where do you see energy being transferred from one form to another? Write down at least 1 example (note the video time), and make sure to explain what object is doing work on what other object, what kind of energy is being transferred, and how you know.

Talk to a partner next to you and share 1 example of work and energy being transferred from one object to another. I will ask several students to share an observation that their partner noticed, and explain to me what object is having work done on it and what kinds of energy are involved.

Possible questions to ask:
What did you see? Be specific, tell me what happened to the object that makes you think there was work done. What kinds of energy do you think that the object has?  How do you know that the object has that kind of energy?

Record student observations on the whiteboard.

[15 min] In-Depth Analysis: Tire

Show video clip of the tire section twice (7 second clip starting at 1:03). Ask students to write down exactly what they see happening to the tire. Have students share their observations, and assemble a record of the tire’s journey on the board to refer to later.  (Make sure that the bucket hitting the tire is included.)  Hand out the worksheet for scaffolded analysis of the tire scenario.

Refer to your handout. Take 30 seconds to answer the first question by yourself. Ask one student to share what they wrote with the class.
1. At the beginning of the scenario, does the tire already have mechanical energy? If so, what form(s) is it in, and how do you know?

Take two minutes to answer questions 2 and 3 with a partner.  Ask one or two pairs to share, depending on time.
2. During the scenario, is work done on the tire by any other object?  Is this work positive or negative, and how do you know?
3. What happens to the tire’s total mechanical energy when the work is done to it?

Take four minutes to answer questions 4 and 5 with a partner. Ask one or two pairs to share, depending on time.
4. Describe what happens to the tire’s GPE, KE, and total ME as it goes through the scenario.
5.  What happens to the tire’s mechanical energy at the end of the scenario?

[15 min] Creative Activity: Design and Analyze

Turn over your handout. Now you have a chance to design your own Rube Goldberg machine! Draw your machine in the space provided, and use the Tire Analysis as a guide to answer the analysis questions below. The questions are due tomorrow for stamps. If you don’t finish in class, please complete the analysis questions as homework.

6. Draw your own piece of this Rube Goldberg Machine that uses 1 object. You must include at least 1 transfer of energy from one object to another.

7. What is your main object in this scenario? :

8. Describe what happens to your object’s GPE, KE, and total ME as it goes through the scenario beginning to end..

9. Where is work done on your object or by your object? How does this work change your object’s total mechanical energy?

10. Explain how your machine obeys the Law of Conservation of Energy, MEi + W = MEf.

Pilot Plant in the Works for Carbon Dioxide Cleansing –

NYTimes is reporting on recent developments in carbon gas capture technologies.

Now a Canadian company has developed a cleansing technology that may one day capture and remove some of this heat-trapping gas directly from the sky. And it is even possible that the gas could then be sold for industrial use.

Love it.

Should the cost of capturing carbon dioxide fall low enough, the gas would have many customers, he predicted. Chief among them, he said, would be the oil industry, which buys the gas to inject into oil fields to force out extra oil.

Does anyone else find anything ironic about the fact that most of the CO2 cleansed from the air would then be used to extract more hydrocarbons for us to burn, thus filling the air with more CO2? Still, it’s an improvement despite the irony — we’d probably burn that new oil anyway, so scrubbing some of the previous pollution before we do it is a net gain.

Gas capture would be extremely important in developing a rational price for carbon emissions, said Dr. Fox of the British mechanical engineering society. “Whatever it costs to take it out of the air and store it away,” Dr. Fox said, “that’s the price polluters would pay if they want to put carbon into the air.”

Bingo. Large industries would no longer be able to complain the value of carbon is arbitrary in a cap and trade program.

via Pilot Plant in the Works for Carbon Dioxide Cleansing –

Jamaica Pond in January

Got a great start on my 2013 photography project of documenting Jamaica Pond month by month. It was a beautiful (though cold) morning here in Boston, perfect for heading to the pond with my friend Jeanette for a photo walk. Adventures were had. As promised, I’m posting some of my favorite shots from today.

The outer edges of the pond are sheathed in a thin layer of ice, which gives way to water towards the middle. Some of the thicker ice supports chunks of snow. This shot tries to capture the interface between the three zones (snowy ice, thin ice, and water:

ISO-200, 1/500, f/4.5, 105mm

In retrospect, I think I should have lowered the f-stop some to get more depth of field. I think I still had it on aperture priority from photographing something up close and forgot to change it (hence the visibly narrow DoF).

There were plenty of ducks out there, puttering about on the freezing water… I really liked the arc of ice leading up to them in this one:

ISO-100, 1/250, f/9, 68mm
ISO-100, 1/250, f/9, 68mm, red filter

I switched to monochrome mode with a red filter in order to darken the water — makes the contrast bolder.

Now, here’s your moment of zen for the day:

ISO-200, 1/500, f/4.5, 105mm
ISO-200, 1/500, f/4.5, 105mm

I used a wide aperture and long focal length to really try and isolate the leaf sitting on a patch of ice.

Finally, here’s a shot of Jeanette taking a shot of the boathouse:

ISO-200, 1/1600, f/3.5, 28mm
ISO-200, 1/1600, f/3.5, 28mm, no filter

So, the 1/1600 shutter speed is overkill and the wide aperture does nothing useful… I think I just took it without bothering to check anything. Despite the apparently spontaneous nature of the shot setup, I do like this one. The vertical black of Jeanette’s figure and the horizontal white of the winterized sailboats from the boathouse are an interesting juxtaposition. I also like how it looks as if I had tree branches in my face… I did.

Plenty more from today, but that’s all I’ll post for now… Can’t wait until the next excursion! I’m so glad already that I took on this project.

What is 21st Century Education?

In PD last week, we watched this video as a precursor to a discussion on how to incorporate more leadership skills into our school curricula and activities:

I love this; it’s a great visual montage of data is continuing to change.  To me this is among the best arguments for designing curricula that go well beyond what we simply want students to know. Because knowledge itself is changing so quickly (and so instantly and comprehensively searchable now to boot), the value of content knowledge for it’s own sake has become necessarily rather dilute.

My only complaint with this video is that it makes it seem like the disconnect between rote content instruction and more authentic learning is some recent deficiency in how we approach education, brought on by the sudden techno-boom of the 21st century. This is not a recent problem which we have been merely a little slow in recognizing.

While the contemporary world certainly comes with unique challenges that we cannot ignore, great minds in education have long railed against the futility of teaching nothing but facts and expecting the process to result in authentically well-educated individuals.

In 1968, Paulo Freire wrote in Pedagogy of the Oppressed:

Education this becomes an act of depositing, in which the students are the depositories and the teacher is the depositor. Instead of communicating, the teacher issues communiqués and makes deposits which the students patiently receive, memorize, and repeat. […] [The students] do, it is true, have the opportunity to become collectors or cataloguers [sic] of the things they store. But in the last analysis, it is the people themselves who are filed away through the lack of creativity, transformation, and knowledge in this (at best) misguided system. For apart of inquiry, apart from the praxis, individuals cannot be truly human. [pg 72]

In 1916, John Dewey wrote in his collection of essays, Democracy and Education:

Why is it, in spite of the fact that teaching by pouring in, learning by passive absorption, are universally condemned, that they are still so entrenched in practice? That education is not an act of “telling” and being told, but an active and constructive process, is a principle almost as generally violated in practice as conceded in theory. [pg 38, III. “Education as Direction”]

That science may be taught as a set of formal and technical exercises is only too true. This happens whenever information about the world is made an end in itself. The failure of such instruction to procure culture is not, however, evidence of the antithesis of natural knowledge to humanistic concern, but evidence of a wrong educational attitude. [pg 219, XVII. “Science in the Course of Study”]

So even without cellphones, YouTube, and Google, these educators (writing 45 and 97 years ago, respectively) understood that a good education (and particularly for Dewey, a good science education) cannot be measured in units of facts-retained.

So why hasn’t anything changed in at least a hundred years or so? What Freire calls the “banking” model of education continues to be the bread and butter of mainline K-12 pedagogy — driven not by teachers, but by the archaic curriculum standards to which they are beholden. Of what value is the ability to regurgitate Newton’s Laws on an exam if the student’s curiosity and ability to engage with humanity’s understanding of the world is left underdeveloped? To be sure, content and curiosity are not mutually exclusive. But in the presence of so much negative pressure from quantitative standards and positive pressure from the ease of rote instruction, where is the weighting of that balance going to inevitably lean?

With the onset of the kind of change highlighted in the video, the imperative for “21st century education” does not become any different, though it certainly becomes all the more emphatic. When Dewey set up his University of Chicago Schools near the end of the 19th century, I think it likely that he made many of the same kinds of arguments that we are making in the early years of the 21st. That means that at least several generations of the status quo have passed by since this idea was proposed. What shall we do now, in the times we have been given?