Friday at Tinkering School is bittersweet. We revel in the joy of spending time here, but we all know it's coming to a close. The kids have the taste for the project now - they can see just what they need to get it done.

We know it'll be a push - there's track to build, a cart to fix, Midway Station to finish. Breakfast is filled with excitement and eagerness - we enjoy the moment, knowing we'll get to have our hands on the project soon.

And then it's off to the workshop - we call the group together for a pre-build chat, and are met with eager faces.

And with a cheer of "T-S-O, T-S-O, T-S-O!" it's off to get started.

The track team surveys the work they've got to finish today - nine track segments have been raised, we need to raise nine more.

We got stilts up on the corners of Midway Station yesterday, but the platform needs more support before it's safe for people. Evan, Milo, and Kevin investigate.

Meanwhile, Xavier tackles the task of repairing the cart door - we've decided that the cattle ramp is too unwieldy for frequent use.

The measuring tapes at Tinkering School are subjected to almost constant fidgeting, and why wouldn't they be? They are coiled springs that suck in a long piece of curved spring steel - everything about a measuring tape is fascinating. Children should be issued a contractor-grade measuring tape when they enter first grade; it's a coiled number line! Milo has had a tape in his hand every day since camp started.

The track team has a system going, lifting and then leveling each track segment as they go, stilting it up and then cutting and adding cross braces.

No train would be complete without the appropriate signage - we want out passengers to know where they are. Anya lends her expertise.

Portrait of a Screw.

Che looks at the camera lens. The camera looks back.

Collaborator Kevin lends a hand as Michaela adds supports to Midway Station.

A peak under the Midway Station platform.

Look at his face.

The track left to level seems endless. The track team forges on.

Portrait of a Bubble Level. This tool is essential to this project, since our goal is to build a level 100+ foot track.

"Take a picture of me!" says Walker. He's discovered a new balancing trick for 2x3's.

This morning, we decided that Terminus Station needed a bench. A place to sit, enjoy, and watch trains come and go is important to a station, after all. So Raquel, Lauren. Anya and Gever decide to build one.

"Oh, is our bench going to be this tall? Can it be a sky bench?" Raquel queried when Gever grabbed an eight foot 2x3, assuming it would be cut into pieces for the project. So, in true Tinkering School fashion, they decide to do it. By late morning the backrest is flying. (And Xavier's made progress on a new cart wall and door system.)

From inside the "Tinker Express," Xavier clamps on his second small wall.

Portrait of a Hacksaw: at work, cutting bolts to size.

An hour after lunch and the bench has a seat, the cart has a door, and we have momentum.

It even holds Tinkerers! How's the view from up there?

Junior Collaborator PK has become the designated "holder-of-track." She's gotten good enough to balance a span on her head. The leveling proceeds.

Raquel adds a ladder to the Sky Bench.

Walker demos proper sunscreen application techniques.

Back at the track, we can feel the progress. Look how far we've come!

Our track supplies us with ample opportunities for cross bracing. Michaela adds a diagonal between stilts.

Evan and Collaborator Serena work together to shore up track legs. By now, they're in sync.

Milo and Caroline have a special connection.

Tall people position the track, little people build trusses. Not by design, it's just the way it worked out on the last couple segments this afternoon as the track grew ever higher.

Hi, Caroline! The crew at Midway works to add rails for the platform.

"I know what we're missing! A Milo Smell Station." We're not sure who's mind, but clearly, this thought crossed someone's. Otherwise titled: "How to catch a Milo."

This morning, we knew it would be a push to get all the work done in time. By lunch time, there was progress, but the work left to do still seemed overwhelming. But we went at it hard, threw our strength into the project, and we got it done. We raised six track segments after lunch, more than we had in any given day up until that point. Midway Station was finished - supports. rails, and even a ladder were built. There's a sky bench, now, as well as a new cart door.

Together, we got there. We committed, and we made it happen. Today, we finish strong.

Then comes the big moment - Terminus Station gets busy as we prepare for our first unmanned test of the full span!

The train gets stuck - Xavier, Kieran, Miles, and PK take a look. Everyone holds their breath.

Turns out, putting a kid in the car solves the problem - the increased mass, and thus momentum, helps get us the clearance we need to get across smoothly.

Rides resume.

And with them, the Superman position. Milo demos. We finish with just moments left before dinner.

Someone left the desktop open - the kids discover the blog. And then, well, there's nothing to be done but read it.

We want the blog to surprise, delight, and make you laugh. Clearly, it works with this audience.

For two years, the Begreenoth (or BGRNOTH as it says on the license plate), Gever's truck, has been in various states of either not working or not at camp. But finally, we get to pull out an old Tinkering School tradition - riding on the running boards. The kids clamber aboard.

Friday night is campfire night - a chance to reflect on our memories and experiences this week, and spend a couple more moments together. Also, fire is fun. Junior Collaborator Gilon leads a team to set up - they build us a nice fire castle.

Some lighter fluid and a lighter later, and we have fire.

S'more stick making emerges spontaneously at Tinkering School, and we as Collaborators take much pride in our pointy-stick-making abilities.

We soak in the moment.

It's hard not to get emotional, on our last night together. If only we could hold time like a squirming child.

We share a closing circle, taking time to share our appreciation for each individual.

We set out to make perfect marshmallows and s'mores.

Mmm, delicious.

PK is an expert at perfect, golden brown marshmallows - tonight, her secret is revealed - she sold her soul.

The fire settles. We take long exposure photos in the fading light. It's a fitting ending to the week - together, enjoying one another's company.

We accomplished what we set out to do - we've built a train, we've built a track. But we've also built a team, and that, in the end, is what matters.

Authored by Serena, with comments and input from Lauren (PK), Gilon, and Gever.

Session A: Day 6 - Photo Finish