Worksheet

0.5 Your own commands

Python quick start · Robot club · about 12 min

What this lesson is about

def, parameters and return: naming a piece of work so the program reads like what it does.

• Naming a piece of work
• Telling it how much
• Why bother

Questions 7 marks in all

1. [1 mark]What happens when Python reads the def side(): lines?

   1. ANothing yet; the lines inside run only when you call side()
   2. BThe robot drives one side straight away
   3. CThe robot drives one side, twice
   4. DPython gives an error until you call it

2. [1 mark]What does this program print?

   def side():
       print("drive")
       print("turn")
   
   side()
   side()

3. [1 mark]What does this program print?

   def hello():
       print("hello")
   
   print("start")

4. [1 mark]What does this program print?

   def side(cm):
       print("forward", cm)
   
   def square(cm):
       for i in range(4):
           side(cm)
   
   square(20)

5. [1 mark]What does this program print?

   def gap_now(reading):
       return round(reading)
   
   print("the gap is", gap_now(27.6), "cm")

6. [1 mark]In def side(cm):, what is cm called?

7. [1 mark]Why is it worth putting a square into a square(cm) function? Choose all that apply.

   Tick every answer that is true.

   1. AThe program says what it does
   2. BA fix happens in one place, not four
   3. CYou can try that piece on its own
   4. DIt makes the robot drive more accurately
   5. EIt makes the program run faster

The task: draw an L

Write a function leg(cm) that drives that far forward and then turns right, and use it twice to walk the robot through both green squares: 40 cm, corner, 30 cm.

from bugbot import *
connect()

def leg(cm):
    # drive, then turn
    forward(50, distance=cm)

leg(40)
stop()

Plan your program here, then type it in and press Run.

Do it on the robot
www.bugbotlab.com/learn/start-5-functions/
The simulator checks it and tells you when it passes. Nothing to install, no account.

Challenges

1. Add a flash() function that blinks the light, and call it at each corner.
2. Give leg a second parameter for the speed: leg(40, 30).
3. Write triangle(cm), and work out the angle inside the function rather than in your head.