Lesson 3.03: Return vs Print

Learning Objectives

Students will be able to...

• Define and identify: return, none, void
• Explain and demonstrate the difference between printing and returning

Materials/Preparation

• Do Now
• Lab - War (Card Game)
• Read through the do now, lesson, and lab so that you are familiar with the requirements and can assist students.
• Note that this lesson may take two days.

Pacing Guide

Instructor's Notes

1. Do Now
   • Students experiment with a function that returns a value, but they must add a print command to output that value.
2. Lesson
   • Ask students about what they think the difference between returning and printing is.
     • Get a volunteer to describe how they rewrote the code in the Do Now to get a value output.
     • Ask a student to write the code on the board.
   • Discuss the concept of the function contract again, explaining that the functions we will work with have both inputs and outputs.
   • Returning is a concept in Snap!, just with a different name: reporting.
     • 
   • If students appear to be struggling with the return vs. print concept, try this activity:
     • Students work together to build a structure using cards. One student volunteer represents the give_card function. This students holds the deck of cards and stands by the board.
     • On the board display the give_card function in code code that only prints the value of a randomly chosen card. Students 'call' the student and request cards, which then the student follows the instructions and draws ('prints') the card on the board.
     • Next display a new give_card function that returns a card instead. Have students 'call' the function, however this time have the give_card student pass out the card when a student calls him/her.
     • Debrief the activity and talk about what was learned.

3. Lab

   • Given a shuffled deck list, students will create a program that plays the game 'War' with the user.

4. Debrief

   • Check student progress and completion of the lab, wrap up by taking any final questions.

Accommodation/Differentiation

As an extension activity, ask students to research the shuffle function and the functions associated with it.