Book Image

Scratch 1.4: Beginner's Guide

Book Image

Scratch 1.4: Beginner's Guide

Overview of this book

If you have the imaginative power to design complex multimedia projects but can't adapt to programming languages, then Scratch 1.4: Beginner's Guide is the book for you. Imagine how good you'll feel when you drag-and-drop your way to interactive games, stories, graphic artwork, computer animations, and much more using Scratch even if you have never programmed before. This book provides teachers, parents, and new programmers with a guided tour of Scratch's features by creating projects that can be shared, remixed, and improved upon in your own lesson plans. Soon you will be creating games, stories, and animations by snapping blocks of "code" together. When you program you solve problems. In order to solve problems, you think, take action, and reflect upon your efforts. Scratch teaches you to program using a fun, accessible environment that's as easy as dragging and dropping blocks from one part of the screen to another. In this book you will program games, stories, and animations using hands-on examples that get you thinking and tinkering. For each project, you start with a series of steps to build something. Then you pause to put our actions into context so that you can relate our code to the actions on Scratch's stage. Throughout each chapter, you'll encounter challenges that encourage you to experiment and learn. One of the things you're really going to love is that, as you begin working through the examples in the book, you won't be able to stop your imagination and the ideas will stream as fast as you can think of them. Write them down. You'll quickly realize there are a lot of young minds in your home, classroom, or community group that could benefit from Scratch's friendly face. Teach them, please.
Table of Contents (17 chapters)
Scratch 1.4 Beginner's Guide
Credits
About the Author
About the Reviewer
Preface
Scratch Resources
Index

Time for action – calculate interest on lump sum


For this calculation, we will allow the user to set the interest rate, but we'll assume a static starting amount of $15,000. You decide whether or not you want to calculate dollars, candy bars, pine cones, or something else entirely.

The formula to calculate simple interest is:

Interest Earned = Principal Amount * Interest Rate * Time

  1. Add a new sprite to the stage. Feel free to choose any sprite you want, but I'm going to select the fantasy13 sprite from the d folder. Name the sprite Lump, as in lump sum.

  2. Create three new for this sprite only variables for the Lump sprite, named lumpSum, interestEarned, and interestRate.

  3. Build the calculation for the Lump sprite. Add the when key pressed block to the Lump sprite's script area. Select the up arrow from the drop-down list.

  4. From the Variables palette, add the set to block to the when key pressed block. Select interestEarned from the variables list.

  5. First, calculate the interest on 15,000 for a time...