Building (math and science) Knowledge

There are different types of knowledge. To know how a square is defined is different than knowing how to identify one. These are different that knowing how to draw one with ruler and paper. Or construct one with compass and straight edge.

A square is a pretty simple example, but when it comes to ramps, bridge, exploring mass and rotation, there’s being able to answer questions about it, and then there being able to build object to create examples, non-examples, and solve challenges. And it can help to have the right tools.

My office recently got a set of Keva Planks. Now, I’ve gotten to see these blocks in action a number of times and they are pretty cool. First, there is almost no learning curve. The blocks are all exactly the same. There’s no connecting pieces or fasteners or adhesive. There’s nothing to them. But with them you can build ramps and towers, polygons and prisms. They set up easily, the clean up easily.

Full-disclosure: They aren’t free. (Cheapest place I’ve found them is Amazon… 400 blocks for $90). Ordinarily, I don’t make a point to advocate for expensive tools, but in this case I think it could be money well spent based on the needs of the location. Also, they are durable and shareable. One department or grade level team could probably make good use with one to share.

Anyway, it’s worth looking in to as they allow us to explore types of knowledge that we otherwise might not be very well equipped to explore. (Particularly with those Next Gen engineering practices that are starting to become a reality in many states.)

For another look, here’s my latest podcast: Instructional Tech in Under 3 Minutes #5 – Keva Planks.


A long-awaited solution (featuring Geogebra)

So, a while back, I posted “Circles from Cedar Street” with an intriguing (at least to me) picture designed to kick off the conversation about rotations.

Then, I left it alone. Like, literally. I didn’t solve it. I should have solved it. I let you down.

I especially let guys like Dan down, who also found the problem intriguing. Sorry about that.

But I realized today that it’s never too late to make it right. So, using Geogebra, here’s is one possible solution to the Circles from Cedar Street problem from back in August of 2013.

Why I love this picture #2

A while back, I discussed why I loved this photo. It’s possible that I have a series starting here (sort of like I have with “Real or Fake”. Anyway…)


Today’s photo is a beautiful example of tech integration because the tech is actually integrated. Integrated with what? Well, in this case, with manipulatives.

See? The student has the problem presented online and will record her answer online, but there clearly is no expectation that the work will be fully digital. Which is a good thing because it can be difficult to ignore how effective manipulatives can be in helping student model and visualize mathematical topics (in this case, 3-D images. She’s building a rectangular prism given the front, stop, and side view.)

That’s why I love this picture.

Perplexity and how it appears…

Here’s a video (by Derek Alexander Muller) I think you should watch.


The critique of #flipclass aside, I’m intrigued by the way the narrator describes the value of “bringing up the misconception”. It’s almost like a thorn that creates some discomfort that only learning will relieve. This gets close to Dan Meyer’s use of the word “perplexity”.

From Dr. Meyer: “Perplexity comes along once in a while. What is it? It’s when a kid doesn’t know something, wants to know that thing, and believes that knowing that thing is within her power. That right there is some of the most powerful learning moments I’ve ever seen – so powerful that it’s really hard for me as a teacher to mess those up.”

There’s power in perplexity. I’ve seen this in my classroom on multiple occasions. It’s important to remember that there’s three distinct parts to creating what Dr. Meyer is describing. First, there needs to be something worth knowing. Second, you have to create the want. And finally, we need to empower the students so they feel enabled to know that thing. What Dr. Alexander suggests is that becoming aware of your misconception seems unsettling (leading to claims that videos were confusing), but also leads to more learning. The discomfort fed a drive to resolve the discomfort.

The tricky thing is that misconceptions are a tool you can use when they are available. Science provides a particularly fertile ground for misconceptions because so much of it is drawn from experiences many of us have regularly. Alexander uses the model of a ball flying through the air. This video uses the phases of the moon and the seasons.

The potential for misconceptions is necessarily lightened when there’s no misconceptions, so the quest for perplexity in math needs to take on a different look, proper planning and timing, and different strategies for when perplexity isn’t an available option. (Preconceived notions are just as good at times. After all, we ALL think we know something about squares!)

It’s like Dr. Meyer says, those wonderful perplexing moments only come along once in a while. We foster those moments when we have them, try to create as many as we can and we do our best every other time.


The Beauty of Geometry

Every now and again, I take the opportunity to simply opine on the beauty of geometry. Math gets a bad rap because of it reputation of being cold, lifeless, functional and academic. (Some folks aren’t helping this by proclaiming that the arts are what we do to enjoy school and math is what we study to get paid later on in life.)

Don’t get me wrong, there certainly are academic ways of discussing art, music, iconography, fashion, design. There’s technique and vocab to all of these areas. Students of these disciplines are still students who must study, but their exploration isn’t saddled with the atmosphere that math is. In math, it is often believed, the box is set; the boundaries drawn. The math frontier is closed. There is no need for exploration when there is nothing to explore.

I’ve always felt like geometry has the capacity to challenge those notions. Kolams, quilts and origami help students understand the aesthetic value of straight lines, precise measurements, perfect circles and right angles. Sometimes, you have to build them to complete your understanding of them. That process alone can bring with it its own supply of feedback. When you are trying to create something visually appealing, often times, the eyeball becomes the expert in the room, not the teacher. Attention-to-detail and technique become valuable without encouragement.

At a recent professional learning opportunity, I was given some time to play with KEVA planks. So I did. The planks are all congruent rectangular prisms. So I placed one on the table. Then I placed a second on with a slight rotation (the diagonal intersection points were designed to sit right on top of each other, but the counter clockwise rotation was determined by the next block being placed so that the vertices were placed on the preceding blocks’ short-segment midpoints. It ended up being about 10 degrees.)

That all sounds pretty mathy (and probably somewhat unclear since I’ve never had to verbalize the process before). But the resulting tower is pretty cool-lookin’ (at least I think.) I simply love when objects with straight lines and right angles are arranged to look like curves. This can happen in algebra as well. As a teacher, of course I don’t know if my students will share my fascination, but fascination isn’t the goal. It’s tough to measure and, besides that, it’s fickle.

I’d encourage you to look for opportunities to change the cold, academic atmosphere surrounding the math. How can we warm this wonderful subject up? We used to take advantage of those tricky days right before a long break and do art projects. Thanksgiving Origami, or build a Christmas (or holiday… or wintertime) scene using nothing but triangles.


What ideas do you have?

Maker Geometry – What can blocks do for you?

So, today I got to play with blocks called Keva planks. A set of Keva planks are nothing more than a whole bunch of congruent wooden rectangular prisms. You can build towers, mazes, bridges, and… of course… geometric shapes.

So, a task came to my mind. Let’s suppose we were going to take the planks and make the smallest possible cube.

  1. How many planks would we need for the combined widths to match the length of a single plank?


The answer’s five, by the way. So, each face is 5 planks wide (which is a single plank long)

Looks kinda like this…


So, naturally… now we can calculate stuff. Like surface area and volume. But to do that, we’ll need some numbers.


So, in my haste,  I clearly did a lousy job of lining up the blocks on the measuring tape. Sorry about that. Not exactly a deal breaker, but annoying.

But since maker materials are becoming more common, I figure you might prefer your students pull their own measurements.

There are a couple of ways that I could see variations of these: different shapes (different kinds of prisms, for example). I could also consider challenges like, given x-number of blocks, who can build a figure with the largest volume or a flat shape with the largest area?

Keva blocks seem like a low-risk, high reward manipulative simply because the start-up would be so quick. What could you do in your class with a set?

Latest Updates to My Geometry Course

My geometry course… funny. It isn’t really my geometry course anymore. Little by little it’s becoming more of a curated set of links that make me wish I still had a classroom. That’s what community will do for you and the innovative math community more than takes care of people. I’ve noticed some excellent learning experiences that my geometry course has been missing. So, I’m adding them. All three are Desmos activities.

Parallelograms in the Coordinate Plane by Jared – This one asks some very interesting questions and has a nice format in which to do it. Due to the algebraic nature of proving this parallel, parallelograms are a nice target for a Desmos activity.

Transformation Polygraph by Julia Finneyfrock (@jfinneyfrock) – Seriously. Check this activity out and then daydream about all the outstanding vocabulary the students would be forced to use while competing with each other.

Working with Dilations by Mr. Rothe – This one is particularly handy because my unit on dilations and scale factor wasn’t my favorite. This is a very robust activity (36 slides), so time might become an issue, but depending on how you run it, I feel like there’s a ton of value embedded in the different learning activities.

If you give any of these a try, please let me know how they go.