After a one-hour lunch break, the notorious Hanwell taggers Kash and Harvey returned to Elthorne Park to continue marking stall pitches for the upcoming Hanwell Carnival. This time, they were joined by Yonas, who had visited the park the previous week to help remove invasive burdock.

The final task of the day for the Carnival started — despite everyone's best efforts to keep the string used for marking rectangle sides tangle-free — with unravelling a long, knotted piece of twine. Fortunately, GoodGymers develop remarkable endurance for untangling strings, Christmas lights and bunting over the course of their volunteering careers, so the knotty challenge was soon overcome.

With the twine restored to working order, the three GoodGymers joined volunteers Sue and Mina for the main job. Rectangle sides were measured, angles checked and then double-checked, sections tagged, and the whole operation repeated for another cluster of stall pitches - all under the scorching sun.

Just when the team thought they were done for the day, they discovered there were two more rectangles left to mark out - and rather unusual ones. Unlike all the previous pitches, whose dimensions had been given in feet, these came in metres: 40m by 18m. That was quite a box to draw!

The continental European GoodGymers had no trouble switching from imperial to metric (in fact, the system made much more sense to them), and the team powered through the final two rectangles, squeezing the last drops from the spray cans to mark the lines on the grass. Luckily, those final boxes didn't need to be divided into smaller sections. Did the European rectangles come with their own Schengen areas? We'll never know.

Before long, the grass-marking operation was complete.

"You are magnificent." - Des, the task owner.

And after a full day of measuring, tagging and line-marking in the heat, nobody was going to argue with that assessment.

The scorching sun had already climbed high above Elthorne Park, and the meadows where Hanwell Carnival was about to take place offered very little shade. Since the morning, Kash had been battling tangled strings, Pythagorean geometry and an acrylic line marker alongside a couple of Carnival volunteers. Luckily, reinforcements were on their way.

At 11:00, GoodGymers Angela, Chris and Harvey arrived to lend the event organisers a hand in setting up Hanwell's big community celebration. Little did they know that their task would involve marking out stall pitches rather than assembling gazebos.

"I've marked football pitches before." - Harvey.
"Great, so we have an expert now!" - Kash.
"No, I wouldn't say that..."

By GoodGym standards, Harvey was definitely an expert - and Angela and Chris quickly rose to that level, rapidly gaining experience on the job.

The team rushed to finish a batch of stall pitches before the midday break (it was really hot, so a break was very much needed!). Perhaps feeling a little too confident, they left one corner of a rectangle unchecked. It soon became clear that the shape didn't satisfy the Pythagorean theorem - in other words, it wasn't straight. The rectangle wasn't really a rectangle at all, but an impostor quadrilateral.

The mistake was quickly corrected, and the rogue white line on the grass was sprayed over with red paint. Kash kept hold of the red spray can to mark the pitch numbers, which turned out to be a lot of fun.

"Kash, you're a tagging natural!" - Chris.

When you think about it, GoodGym offers a rare opportunity to do graffiti-style tagging without being accused of vandalism. How cool is that?

Having marked and divided the large rectangle into smaller pitches, the team moved on to six more boxes around the crafts tent, which was still being erected. The speedy GoodGym crew finished their grass graffiti before the tent was completed and just in time for a well-earned lunch break.

Great work, everyone!

I took a day off work on the Friday before Hanwell Carnival to help set up the largest single-day carnival in London. It was a lovely, sunny morning, and I was looking forward to dialling down my brain activity while doing some fun, physical GoodGymming — think setting up gazebos!

"How good are you with maths?" — Sue, the Carnival volunteer.

Wait, what? So there was no escape from number crunching today. At least we were going to do it in real life. Sue and I, later joined by other volunteers, had a task to mark out all the pitches for the stalls that would be set up later. And the stallholders were bringing their own gazebos to assemble themselves! No gazebos, no shade... Well, I was up for a new experience.

Sue and I grabbed tape measures (which were abundant) and metal pegs (not so abundant) and started drafting the imaginary layout of the stalls based on Sue's map. We had to make sure that the rectangles we marked out — the first one was a whopping 60 by 30 feet — had proper right angles. Luckily, we weren't tested on our mental arithmetic by having to apply Pythagoras' theorem ourselves, as the measurements for the sides and diagonals had already been worked out. Phew!

Having marked all the rectangle corners with pegs, we then had to use orange string to outline the sides. Here's where the complication began. If you've been to a few GoodGym sessions involving event setup — with twine, bunting and other things that love getting tangled — you'll know exactly what that means. The string was, of course, tangled. Our predecessors must have been in a hurry and left the twine to joyously develop knots and loops designed to test our patience.

With two brains and four hands, Sue and I managed to unravel the string, which, just like Ariadne's thread, led us to our goal (no Minotaurs involved): a perfect rectangle ready to be marked with white spray paint. I had the honour of driving the machine normally used to mark football pitches. So far, I've managed to avoid getting involved in discussions about the World Cup, but apparently I couldn't escape football altogether!

As Sue and I marked out the internal sections of our giant rectangle, volunteer Mina arrived to help us with the next stage of the task.

Who would have thought that Greek geometry and Greek mythology would be the most useful subjects for marking out carnival stall pitches?