Big Rocks First

My Secret to Beginner-Focused Lesson Planning

I have been teaching folks how to build their own websites and web apps for four years, collaborating with three fabulous Chicago institutions: Northwestern University (business students at the Kellogg School of Management), the University of Chicago (an elective in the Masters Program in Computer Science), and The Starter League.

I write my own lesson sequences from scratch and develop all of my own materials, with amazing success at all three institutions.

I’m often asked what makes my courses so successful. When I’m teaching true beginners, having the right lesson sequence is critical. Every quarter I find ways to improve the sequence a bit, by following a guiding principle I call Big Rocks First.

Rocks, Sand, and a Jar

I first encountered this puzzle watching a Bill Nye episode a long time ago:

You have an empty jar, a half-jar’s worth of fine-grained sand, and a bunch of big rocks. The rocks will easily fit through the mouth of the jar, and take up less than half the volume of the jar.
Unfortunately, the rocks won’t stack nicely. They take up 7/8 of the height of the jar even though they will use less than half the volume.
How would you fit all the rocks and sand into the jar?

If you put the sand in first, the bottom half of the jar will be full, and the rocks clearly won’t fit in the remaining space. They will reach above the top of the jar, because they need the entire height of the jar, and you’ve already filled up the bottom half with sand.

The answer is also the key to writing lesson plans: go with the big rocks first. They will take up 3/4 of the height of the jar but less than half the volume. Then simply pour the fine-grained sand around the rocks, and everything will fit.

Some things are important to learn right now. Other things are not.

For every topic, textbook chapter, or new idea, there is one main concept that is important. That’s my big rock. That goes first.

There are other things the students must learn that are smaller. That’s my sand. It goes in last.

I must not allow my students to spend their attention on the minor details. If students fill their memory capacity with minutia, they won’t have room for the big concepts.

I deliver the big concept first while limiting details. I make sure they get the big idea first. I pretend the details don’t exist. I don’t indulge questions from students who want to run ahead to unnecessary details until they demonstrate that they get the big concept first. I lie if I have to, to make sure they focus on the rock. Then, they will have sufficient context and space for smaller ideas and facts.

The next time you’re teaching a new topic, idea, or section in a textbook, work hard to identify the biggest rock. (Typical math and science textbooks don’t do this very well, so you’ll need to improvise.) Cut through the noise of tedious problems, and help the students focus on the main idea.

Get that big rock into their mental jar first. All the rest of the sand will easily follow.