The Tuesday of Tinkering School marks a shift from "anything is possible" to "we're never going to be done in time" - particularly with this age group. It is one thing to build some track, it's an entirely other thing to build 180 feet of flat and level track over hilly terrain. Or to raise a flat deck on a slope that has been swiss-cheesed by gophers. Or to make a train that will roll smoothly, and not derail, and handle a high-speed launch ramp. Or to make a launch ramp that actually works and doesn't injure the passengers.

It all started with Gever and his morning Structural Engineering 101 session.

Today's lesson: the power of levers.

The solution to resisting the power of the lever is the power of the triangle, and now our camp has a gang sign.

After our brief lesson, it's time to get to work.

The City team has to work out some tricky details in order to raise and level the deck. The first problem is that the deck is about as rigid as a cooked lasagna noodle right now.

With the rest of her team helping out other projects, Gigi represents for Team Panda and keeps pushing the launch system to completion.

The porthole always gives delightful views of tinkerers, as demonstrated here by Zeke.

Team Nooi took on the Train Project, and while one sub-group works on the rolling deck, Eloise, Hayden, and Corin build a new, improved body for the train.

Sasha is part of Team Kablooi, and she's been relentlessly productive all day, working on the tracks.

The fifth iteration of the wheels and guidance system is taken for a test roll. So far so good, but they will soon discover that it is now incompatible with the launch system...

Portrait of a Tinkerer: Lee saws the protruding ends off of railroad ties to allow cross-beams to achieve a co-planer join with the rails.

How's that mouthful of Cheez-Its, Gever?

Portrait of a Tinkerer: Rodrigo has been on it, all day long!

Lily checks out the view from the cart-base: it's cooler lying on your belly.

The Kablooi track building sub-team has been churning out track all day, and they have it down to a science - part of their process is pre-drilling each railroad tie on both ends, in preparation for mounting. Apparently, spontaneous mustache appearance is to be expected. Just look at that lovely detail...

Tinkerers run primarily on fruit and goldfish.

Checking in with the team Piki out in the field reveals that the deck is coming along nicely. Steady progress. The group is determined.

Bullet #8 - "Always be Knolling."

Alex and Gever discuss a tricky problem - because the guide wheels aren't compatible with the launch ramp, the cart chassis will require a redesign. Specifically, the guide wheels need to be moved in further, which means repositioning the bungee that keeps them in tension.

Rodrigo, Lee, and Zack have a system going - they work together to consistently raise and stabilize track.

A close-up on the action: Zack helps Rodrigo align his screw.

When the launch system got stalled, Gigi headed straight for the next team which could use her hands. Here she is, adding stabilizing triangles to brace the legs which hold the track up.

The track team decided on a major redesign for the track supports this morning - if it works, it will greatly reduce both the number of custom measure-and-cut-to-size pieces we need to get the track up, as well as our wood use. Which means the first segment we put up was really a prototype - Rodrigo and Lee combine their weight to test its strength. It holds!

The track withstood the first test - now, will it support the weight of a tinkerer from above? Rodrigo ventures out on the segment he just recently helped to build. We conclude that this track design will suit our purposes nicely, and agree to pursue it. Yay!

Lily works to sketch out our new track design.

A group gathers for a snack break and a chat. We're making good progress, and it feels good to check in and catch up with friends over apples and trail mix.

The deck team has just finished flooring their deck. They celebrate!

David is fast becoming an expert at measuring tape fishing.

Portrait of a Tinkerer: Claire catching her breath after building track all day.

Portrait of a Junior Collaborator: Kieran

Portrait of a Junior Collaborator: Elijah

With new track growing rapidly from Midway Station towards Tinker City, Tyler decides it's time to remove the train stops and open up the new railway section. I wonder if we remembered to put in a new set of stops...

Maybe a hastily written sign will do the trick.

Meanwhile, out at Tinker City, there's a new kind of problem to solve: gopher holes!

We've made a lot of track over the past three weeks, but this innovation has enabled an entirely new kind of distributed productivity; there are independent sub-teams producing parts, making sub-assemblies, and installing units of track. Particularly helpful is the collective agreement on the names of parts.

Anna, Sasha, and Claire work through another set of possible solutions to the 16-foot bridges that are coming up. Zeke is new to the track team, so he's just soaking it all up.

We're going to lift this deck, using all the strong muscles of our lower backs - ready?

And that's nicely done. Now hold it there while we measure the distance to the ground in all four corners, and the four corners of the opening.

And now let's put it down, work on reducing the noodliness, and we'll call you back when it's ready. Thanks!

And lift again, we'll get it level and re-do the eight measurements. Ready?

And we hold it steady so that Sophia can take an accurate measurement.

The measurements in the inside are not only tricky, they are a little risky because the deck is held entirely by the hands of distracted (mostly) teenagers.

And we're done. We'll cut some posts after dinner, but for now we can relax.

Serious amounts of track have been produced today!

We all do it, but this is Dylan eyeballing the track to check level and flat.

After dinner, a group of intrepid tinkerers sets out to climb the ridge above the ranch and get a view of the sunset.

And this is the beginning of how they got lost: let's get off this main trail and see if we can just go straight up to the top of the ridge. Sure, what could possibly go wrong? "Hey Jack," says Serena, "I wouldn't be following you if I didn't think part of Tinkering School is being a little bit stupid now and then."

Before they got all bedraggled and cold.

The sunset was amazing, but now, all of a sudden, they lose the light and the "trail" is abandoned for a new "more direct" way down.

But, with the help of Elijah and Gever coming up from the conference center in the BGRNOTH, the way back to the trail is clarified and we all head back for cookies hot out of the oven and a Marx Brothers movie. All in all, a fitting end to an exalting adventure and a most excellent day.

Tonight's blog brought to you by Gever, Serena, Daniel, and Corin.

Session C: Day 3 - Working Hard, Getting Lost