Robot Directions & Sequencing

An algorithm is a sequence of steps that solves a problem. Every program you have ever used runs on algorithms.

When you build a command sequence to move the robot, you are writing an algorithm. The robot follows each step exactly as written.

• Step 1 runs before Step 2
• Every step must be clear and specific
• The robot does not guess or improvise

The same set of commands in a different order produces a completely different result. Try it with the robot.

"Forward, Turn Right, Forward" takes you somewhere different than "Turn Right, Forward, Forward." This is why programmers must think carefully about sequence.

• Swapping two steps can change the entire outcome
• Order is one of the three core ideas in programming (along with loops and decisions)

When a program does the wrong thing, programmers debug it by reading the steps one at a time to find the mistake.

If your robot does not reach the star, go through your sequence step by step. Ask, "After Step 1, where is the robot? After Step 2?"

• Use the "Step" button in Learn mode to trace step by step
• Look for the first command that gives an unexpected result
• Fix that command and re-run

Every app, game, and website you use runs step-by-step instructions like the ones you are building here. Computers are very fast at following these steps, but they follow them one at a time.

• A game character moves based on a sequence of physics steps
• A search engine follows steps to rank results
• Your phone alarm follows steps to check the time and ring
• Robots in factories follow motion programs just like this grid robot