Repeating Without Rebuilding

Try It — Thirty Small Hops

Back in Project 9 you moved the arm in three big jumps and were asked what it would take to move it in thirty small ones. Here is the answer you were promised.

Read it with a partner before you run it, and answer these from the blocks alone.

Now run it with your own arm numbers and watch.

How is this different from a single run C to position (arm up) block on its own?

Where the counting lives

Look at that loop again. The three things that control the counting are in three different places: the start is in the set block above the jaws, the stopping point is in the hexagon, and the step is buried inside.

If a teammate asked you “how many times does that run?”, how long would it take to work out — and where would your eyes have to jump?

Learn It — The Loop That Counts For You

When what you really mean is “do this N times,” there is a block that says exactly that — and the count sits right on its face where anyone can read it:

No variable to set, no hexagon to aim, no step to hide. The loop does the counting for you. You have already used it once — the repeat 4 in your drive square, back in Project 12. Now you know what family it belongs to.

Three loops, three jobs

Repeats hold anything

Jaws are jaws. A repeat can hold your My Blocks, an if-then-else, even another repeat. The square is a repeat holding two of your blocks; a two-tier pom run is a repeat holding fetch-and-drop; the smoother is a repeat holding a change and a move. Same block, every time.

Do It — Do It Again — Automatically

Step 1 — Build the smoother

Duplicate your Toolbox for this project. Build the Try It smoother with your own numbers, then wrap it in a My Block called arm up gently, and make arm down gently to match — same loop, counting the other way.

• My arm creeps up and down gently, each as one block

Step 2 — The square, one last time

Rebuild the square as repeat 4 { drive forward 24 · turn right 90 } — three visible blocks in the main stack.

• My square is a repeat 4 and still closes

Step 3 — Mission 11 Bonus — two orange poms7 pts

Start here — it is the simplest “do it twice” on the field, and you already own the block.

The second pom is somewhere different, so your block needs an input or a short drive between trips. Same problem you solved for Mission 15 in Project 12.

• Two orange poms are in the same basket at the end

Step 4 — Missions 16 and 17 Bonuses — stack them higher22 pts

• Two spilled cubes are on the Large Green Cube at the end
• Two unstraight cubes are on the Large Brown Cube at the end

Did the second delivery ever knock the first one off? What fixed it?

Step 5 — Mission 7 Bonus — a second enclosure9 pts

This is the same delivery as the base, aimed somewhere else — which is exactly the case for a block with an input called twice, or a repeat over two destinations.

• Two enclosures each hold a blue and an orange pom

Step 6 — Put the loops in your Toolbox

Anything you wrapped in a loop that worked — deliver poms (how many), arm up gently — belongs in the master Toolbox. Add it there first, and note it in your team instructions.

• My new loop blocks are in the master Toolbox and written in the team notes

Step 7 — Run it five times

Score It — Checkpoint

My score

Which loop?

Pick the right tool: repeat N, repeat until / wait until, or a counter in the jaws.

How many times?

From the blocks alone, how many trips through the jaws?

That last one is legal and runs. What does it actually do, and why is it a trap?

Can you do it again?

• I can pick between repeat N, repeat until, and a counter — and say why
• I can read a counter loop and work out how many times it runs
• My arm can creep to a position instead of snapping there
• I can turn a “do it again” bonus into a repeat around a block I already own
• I can put my own blocks, ifs, and repeats inside a repeat
• My smoothers live in the Toolbox now, master first

Every point on the field

Add up what you scored across the whole strand. The right-hand column is what was available.

Think about it

You have built four kinds of loop question now — a switch, a wheel count, a brightness, and a plain count. Which was hardest to get right, and why that one?

In Project 1 you ran a program somebody else wrote and did not understand a line of it. Go back and read that program now. What does it say to you?

Your robot does exactly what it is told, every time, and has no idea what any of it means. After seventeen projects, does it seem intelligent to you? Say what makes you answer that way.

That Is the Coding Strand

Seventeen projects ago your robot could not be switched on. It now drives measured distances, turns to an angle, grabs and stacks and places, feels for walls, counts its own wheels, reads light and dark, follows a line, checks its own work, and decides what to do when something goes wrong.

All of it built from about a dozen commands and four ideas: do this, do it if, do it while, do it again.

Take your Toolbox with you. Next season the field will be different and most of what is in that project will still work.