Challenge 1
List every scoring action on the farming set as its own row: what the robot must physically do, what it is worth, and what it depends on.
The mission 4 min
Plan the farm — and decide which legs are worth being fast on.
You have costed a route before. Today adds one question on top: of all the legs in your plan, which ones would actually give you seconds back if the robot drove them harder?
Speed is not free and not uniform. Making a short hop between neighbouring stations faster saves almost nothing and risks overshooting the station. Making a long diagonal faster can save real time. A team that tunes every leg for speed will spend this entire block tuning.
The farm, corner to corner 5 min
Seven stations, and this time they reach every corner of the mat:
- HOME — the loading yard, top left. Start and finish.
- A — the market barn, along the top.
- B — the vegetable stall, top right.
- C — the greenhouses, in the middle of everything.
- D — the pond.
- E — the compost heap, bottom left.
- F — the packing table, bottom right.
Notice the shape. HOME and F are diagonally opposite, as are E and B. Those diagonals are the longest journeys on the mat. Meanwhile A and B sit near each other along the top, and C is central enough to be a short hop from almost anywhere.
So this mat has two completely different kinds of leg, and they want different things from the robot. That contrast is what the whole block is built on.
The technique — where speed actually pays 12 min
Take each leg of your route and ask three questions. The answers decide where the rest of this block gets spent.
- How long is it? A long leg has room to gain. A short one is over before the robot reaches speed, so a faster setting saves fractions and risks the arrival.
- What happens at the end? If the leg ends at a station where the attachment has to work, arriving badly costs far more than arriving slowly. If it ends somewhere you can square up, you can afford to be rougher.
- Is it repeated? A leg the route uses twice is worth twice the tuning.
Fast and reliable are in tension, and this block makes you pick a point on that line. Lesson 31 asks for the fastest settings that still finish ten runs out of ten — not the fastest single run. A setting that wins once and fails twice is worth less than a slower one that always finishes.
Now mark, on your route card, the one leg worth the fastest possible following. One. Usually a long diagonal — the loading yard down to the packing table, or the compost heap up to the vegetable stall.
That leg is not just a planning note. It is the leg lesson 27 will break proportional control on, lesson 30 will race three followers over, and lesson 31 will push to its limit. Choose it deliberately and write it in the journal.
Build it — on paper 10 min
Three artefacts today, and lesson 26 needs the third.
One — the costed route card. As in lesson 17: station order from HOME back to HOME, a time beside every leg and action, a total inside the round, and the missions you cut.
Two — the speed marking. Beside each leg, write fast, careful or short. Exactly one leg gets marked as the fast leg.
Three — the attachment sentence. Different from previous blocks in one specific way: this mat wants one attachment that serves two missions, so that nothing has to be swapped mid-run. Your sentence must say what both jobs are and what shape does both.
The program — in blocks you already own 12 min
Pseudocode again, written in your My Block names. After three blocks the vocabulary is large — Follow Line, Move Straight, Turn By Degrees, Square Up, Collect, Calibrate Gyro — and most of the farm route is already expressible.
Then annotate each call with the speed marking from your route card. Follow Line takes a speed input, which you added in lesson 14, so a careful leg and a fast leg are the same block with different numbers.
That is the reward for lessons 13 and 14 arriving when they did. This block can spend its time on control theory rather than on plumbing, because the plumbing was finished two blocks ago.
Tune it — defend the fast leg 9 min
Three questions, answered as a team and written down:
- Why that leg? Length, repetition, or a forgiving ending — say which.
- What would going faster cost you? Name the failure you expect: overshooting the station, losing the line on a bend, or spilling the attachment.
- Which leg must never be rushed? Usually the one ending where the attachment has to work. Mark it, because it is the leg you will be tempted to speed up when the clock beats you.
Run it — the walk-through 6 min
Block 3’s robot on the mat at HOME, pushed by hand along the planned route while somebody reads the pseudocode and a third person times it.
Time the marked fast leg on its own as well as the whole route. That single number is the one this block will move, and you want to know where it started.
The journal 4 min
Today’s entry opens Block 4:
- the mat sketch, corrected in colour
- the costed route card with the speed marking on every leg
- the fast leg, named, with its walked time and your reason for choosing it
- the leg that must never be rushed
- the attachment sentence, saying what two missions one shape has to serve
Bring Block 1 and Block 2’s follower times. Lesson 30 puts the two-state follower from lesson 5, the proportional one from lesson 12 and the PID one from lesson 29 side by side over one leg. Those old numbers are two thirds of that table.