How to Teach PEN Lessons

The main goal of PEN lessons is not to have students remember things by heart, or get good grades in tests. We're not concerned how long it takes students to learn something, but how fully they understand it in the end.

Ideally, students should understand the experiments and projects so well after doing them they could build them themselves without the help of a teacher!

(Note: you don't have to be a “teacher” to teach a PEN lesson! If you're a student looking to start a PEN club or do one of our projects, these are good tips to keep in mind for going through the lessons with the rest of your group)

Let students discover things!

Studies have shown that we remember:

  • less than 10% of something we read or is told to us
  • 50% of things that are demonstrated to us
  • 70% of what we discussed with others
  • 80% of what we experience hands-on
  • 95% of what we teach

With this in mind:

Encourage group discussions and collaborations

  • Try to lecture in front of the class as little as possible - instead, start a class discussion about the topic. What does the group know about the subject? What do they think might be happening?
  • This works better with a smaller group. If you have a large class, try introducing concepts to the whole class then dividing into groups for discssion.
  • For hands-on experiments and building - even if each person is building their own experiment or project, it helps to build in small groups. Students can discuss the concepts, figure out things together, and lend each other a hand. Two people can build two things faster than one person can build one thing!

Ask questions, don't tell answers

If a student is having trouble figuring out a concept themselves, try asking questions to get them to think about the problem in a different way.


“what do you think would happen if…[we did the opposite of what we're doing now]”

“can you think of anything else that acts like this?”

Let students teach!

If some of the students “get” concepts before the rest of the class, let them explain it to the rest of the group. They might be better at finding the right ways to get concepts across than you are!

As much hands-on as possible

Although managing a large group of students doing practical activities can be complicated, try to give the group as much time to experiment freely as possible.

For instance, a test setup could be built in specific steps, but then the experiments done by the students individually.

If it is impractical or too dangerous to let every student try an experiment themselves, still avoid giving the answer directly. Have one person – yourself or a student - do a demo and let the other students observe, discuss, and speculate for themselves on what is happening.

Encourage Design

One of the most important and empowering things students can learn is how to design well: how to take a problem, come up with their own solution for it and figure out how to build or implement it.

The most important thing about design is that there is no right answer!

There may be “good designs” and “bad designs” but there is never a single perfect solution to a design problem.

This is what makes design different from science or maths problems. If you ask ten people what 2 + 2 is, we would hope they all answer 4. However, if you ask ten people to figure out a way of attaching a wind turbine to a roof, we would hope they all come up with different designs!

However, many students will be used to there being “one right answer” - so how do we encourage design?

Describe, don't show

If you show a version of the design that you've built earlier, the rest of the group might think of that as the “right answer”, and you'll end up with a class full of very similar designs!


  • Try to describe a design in terms of functionality. For instance, if describing how to build an anemometer, don't say “you can make the cups out of cut-up bottles”. Say “you need something with a cupped shape catch the wind - what can you think of that does this?” Or rather than suggesting an LED to stop a solar circuit from discharging ask “what do you know that only lets current flow one way?”
  • Draw shapes on the blackboard or demonstrate them with paper - then get rid of them! Make sure the group knows that your suggestions aren't set in stone.
  • Try not giving everyone the same materials to work with. For small design projects, gather collections of scrap material and give each group a different set to work with. This forces groups to come up with their own designs. It's also a good demonstration that there is no “right answer” - two different groups with two different sets of materials can both come up with a good solution to a problem!

Local materials

PEN lessons are designed to be flexible and able to be taught where you're in San Francisco, Accra or rural Nicaragua. Often the lessons will not list specific materials, but instead specify the functionality of a material.

Some items, like solar cells or non-standard electronic components, are difficult to find and need to be either specially ordered or extracted from e-waste. See the getting.materials page for more details on how to source parts.

Why use local materials?

As well as making the lessons adaptable, the other reason we'd prefer to use locally-available materials is because it helps students relate more directly to science and engineering principles. If students can see where parts come from, then science becomes something not confined to a textbook, blackboard or classroom exercise but relevant and observable in all aspects of their lives!

Locally available doesn't necessarily mean objects that students will encounter in their every day lives - many projects are too complicated and require some specialised materials. Local could mean bought from a shop in the same town, or extracted from a piece of equipment - but make sure to let the group know where you got it from!

Explain that materials live outside the classroom too

Even if you're using ordered parts, make sure students don't just see them as equipment that is only used for classroom experiments! Show them and give examples of where the parts are used in real life. For example:

  • Show how LEDs are used in torch/flashlights, the on/off lights in electronic equipment, etc
  • Small solar cells are used in some calculators
  • DC motors are used in fans (desktop fans, computer fans)

The students might even have seen the parts at work in places you haven't - ask them what they can think of that uses these parts!

“Local Materials” Example:

A successful early PEN lesson was “salt-water batteries” - making battery cells using only water, salt, charcoal and coke cans.

The students were very excited about the batteries - more so than they were about other lessons taught using materials shipped from the US - because they could repeat the experiment on their own without needing resources from a teacher. Also, because it involved materials they were familiar with, they were more comfortable asking 'what if?' questions: what would happen if I used a different material, what if I used a bigger can, what if I put in more salt?

In the lessons taught with ordered materials shipped in for the lesson, the students were less familiar with the materials, so more hesitant about asking questions.


Ned, 2012/01/10 01:24

(begin stream of consciousness:) The intro is awesome.

“Studies have shown” is insufficiently scientific. :p

Also, think about problems at extremes: “what if here a hurricane, or your turbine was a wall? MAGNETS!”

No right answer YUSS. Same for functional description.

Anna's comments raise good points; it might be worth talking explicity about classroom power dynamics (and, as a corollary, gender).

I'd also add that clear goals / 'teasers', group introductions, and intentional error are useful bits for teaching. (and if they seem worthwhile bits, I can write something about it)

Anna, 2012/01/09 08:17

Excellent start! I particularly like the 'local materials' section and rationale, and the suggestions for why and how to encourage design rather than the 2+2=4 thinking about problem-solving.

One useful section might be 'ways in which PEN classes are different from normal classes,' or something like this to acknowledge that these classes might at first seem very strange. Or this could be integrated into the first section, but we should include more emphasis on 'allow this lab to be a different experience from the rest of the students' classes.' PEN classes should encourage students to brainstorm suggestions that can be wild and outright wrong, and the teacher should write these up on the board without worrying that the teacher will seem inexperienced for accepting this ridiculous suggestion. PEN students should be allowed to talk to their peers in small groups, even while other students are talking to their own groups– in other classes, a student might not be able to speak at all without raising her hand and then standing up while she talks.

We'll have to be careful about how to encourage these 'strange' behaviors without having teachers feel threatened, or feel like they're losing control over their own classrooms…

(Perhaps we can also address a teacher's fear that she doesn't know enough about the subject to let the students ask questions. Maybe we can convince teachers that, if students ask questions teachers can't answer, this is a great thing! It just means that the student is thinking intelligently, and people will have to do some research outside of class.)

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