Congratulations on building your DJ mixer.

Today you're gonna use some of the core computer science concepts you already know by using forever loops to repeat and action and using an event to capture a keyboard press from the person using your computer program.

You also learned a really important computer science concept, variables.

Use the variable to distort the position of the sliders so that you can use your value in your code.

The code bot knows to look inside that variable for how long the computer should wait before performing an action.

So if the variable changes the wait length changes also.

Variables are also used in nearly every computer program.

Computer scientists use to store the cost of an item in an app so that people can buy and sell clothing with one another.

A variable stores the scores in a racing game app and stores the price of homes in a real estate app.

Although variables exist in computer science, they can also apply to any field that interests you.

From gaming to retail, and even real estate.

You can use computer science to build all kinds of apps and tools for the people to use.

When you take a computer science class in the future you'll learn even more cool and fun ways to use variables.

When you get there you'll be ahead of the game because you already made and used variables in Scratch.

The next time we meet in CS First you'll build your own music video with songs, characters, and special effects.

  • Ocado Delivery Slot by Tony Hirst ( licensed under CC-BY 2.0 (
  • Trulia iPad app property details by Ken Shuman ( licensed under CC-BY 2.0 (
  • Space Wars Intergalactic by panda33a ( licensed under CC-BY 3.0 (
  • The song “Festival” is © YouTube-- CC-BY-SA 4.0 does not apply.