Part 1: Procedures

• Introduce the concept of procedures by singing a song with a chorus with the group. Start with a simple song, either written out or projected on the screen.
• Point to where the chorus is printed (above the verses) and be sure that the group knows how it goes before you begin the song.
• Blast through the song, singing it with them in the beginning. Then see what happens when you get to the part where it calls for the chorus.
• It's quite likely that the majority of the group will sing the lyrics for the chorus when you point to that bit. Stop the song once that happens, and highlight what just happened.
  • You defined the chorus.
  • You called the chorus.
  • They sang the chorus.
• Ask: Why do you suppose I only wrote the chorus once at the top of the paper instead of writing it over and over in each place where it is supposed to be sung? What are other benefits of only writing the chorus once when you sing it many times?
• Now, ask the girls to imagine that this song is a computer program.
• Introduce the computational thinking concept procedures. Explain that defining a title (like chorus) for a little piece of code that you use over and over again is called creating a procedure. This strategy is helpful to computer scientists for the some of the same reasons that it is helpful to songwriters:
  • It saves time not having to write the code over and over again in the program.
  • If you make a mistake, you only have to change it one place.
  • The program feels less complicated with the repeating pieces defined just once at the top.

Part 2: Parameters

• Ask the girls to think about songs where the chorus isn't exactly the same every time. Could you still use a chorus? The answer is yes, but you have to have a way to let the singer know what special words to use for each verse. These special words are called parameters.
• In programming, parameters are passed as special instructions to procedures like this:
  • chorus(parameter1, parameter2)
• Explain to the girls that to understand parameters they're going to look at songs again. This time they're going to look at songs that change during each repetition of the chorus.
• Have girls get into groups of 3 or 4.
  • Play a short song for the group that contains a clear chorus that does not change from verse to verse.
  • Challenge the group to identify (and write down) the chorus.
  • Compare results from each group. Did everyone identify the same part of the song as the chorus?
  • Give each group several copies of the Songwriting worksheet
  • Try the activity again, but this time with a song that changes during each repetition of the chorus. Good examples are: Old MacDonald, Baby Bumblebee, or The Hokey Pokey
  • Ask: Is it harder to identify a chorus when some words change? How might you use the same idea of calling a chorus when the chorus is different from verse to verse? These changing words and phrases are called “parameters” and you can pass them into the chorus like this: chorus(cow, moo).
  • Play this game over and over until the group has no trouble identifying the chorus. It is often easier just to have the group listen to (or watch) the song, then vote on what the chorus is by singing it together, rather than writing the whole thing down.