Lesson 2.4: Variables <---- Formerly 3.1 ---->

Learning Objectives

Students will be able to...

Duration	Description
5 minutes	Welcome, attendance, bell work, announcements
15 minutes	Lecture and introduce activity
25 minutes	Activity - Guessing Game
10 minutes	Debrief and wrap-up

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
Activity
- Briefly demonstrate the block, which will be used in the lab
- Direct students to complete Guessing Game individually or in pairs
Debrief
- Discuss and demonstrate one or more students' submissions
- Ask students for commentary on usage and naming of variables throughout program

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