1. Exploring Computer Science Lesson 4-12
Timers
Exploring Computer Science
Lesson 4-12

2. Objectives
The students will be able to:
Create a timer

3. Timers Timers are simply a variable that counts down (or up).
You already know how to initialize a variable
You know how to add or subtract one
You know how to “wait” 1 second
Bottom line – You know how to make a timer! I don’t need to teach you.

4. Timer Project How to make a timer in Scratch:
Create a variable called timer.
When the flag is clicked, initialize the timer to 30.
Continually, wait 1 second and subtract one from timer
Output the current time either with a sprite or just show the variable
Check if the timer = 0
If the timer = 0 make either the background or a huge sprite say “Time’s Up”
When the green flag is clicked, everything should start over.
Be creative as to what you want your program to look like.
Make sure the timer stops at 0 and does not continue into negatives.
Extra Credit: When the time’s up, have the sprite or background also say the score.