Lesson 3.1: Variables

Learning Objectives

Students will be able to...

• Use variables to track values throughout a program

Materials/Preparation

• Lab 3.1 handout - Guessing Game (Download in Word) (Link to PDF)

Pacing Guide

Instructor's Notes

1. Lecture

   1. Review user input, specifically the block
      • Ask students to speculate about how the block works
        • Students should recognize that the block must be storing a value somehow and remembering it for later
      • Ask students whether that type of functionality might be useful in other cases
   2. Introduce variables
      • Define and explain the concept of a variable
        • a "place" to store a value for retrieval and use later
      • Demonstrate creating, assigning, and accessing a variable in SNAP
        • Ignore global vs. this sprite only for now
        • Point out that a variable can only hold one value at a time
          • When a new value is assigned, the old value is lost and cannot be recovered
        • Emphasize the importance of descriptive, readable names for variables
      • Show that variables are independent
        • One variable's value can be assigned to another, as in , but changing the value of var2 later will not update the value of var1

2. Activity

   • Briefly demonstrate the block, which will be used in the lab
   • Direct students to complete Guessing Game individually or in pairs

3. Debrief

   • Discuss and demonstrate one or more students' submissions
   • Ask students for commentary on usage and naming of variables throughout program

Accommodation/Differentiation

• Advanced students can be encouraged to implement statistics (best score, average guesses/game, number of time each secret number chosen, etc.)
• Struggling students can be given code that completes part 1.1, and possibly also part 1.2, to get them started
  • Students who are particularly overwhelmed should focus only on parts 1.2 and 2.2