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Preview of the Scratch program

Now it's time to write and discuss a Scratch program. You should be able to replicate this program.

Hopefully by now you have worked your way through the Step-by-Step Intro and the various tips that you can access by clicking the question mark on the right side of your browser window when the window is open on theScratch website's programming interface . (Click the Create link on the Scratch website to open the programming interface . )

Hopefully you have also worked through several of the tutorials that you can find on Scratch as recommendedin the previous module. If not, you should do that before continuing with this module. In other words,by now you should have experience moving Scratch blocks around to cause your sprites to behave as you want them to behave.

In case you skipped the section titled An overview of computer programming , you might still want to go back and review the section on Variables .

The Scratch program named Variable01 .sb

Click here to run this program in your browser.

This Scratch program illustrates the creation and manipulation of two simple numeric variables.

Scratch variables can contain numeric values or strings of characters but this program will deal only with numeric values.

This program also illustrates the case sensitivity of variable names along with the ability to detect and respond to events fired by the keyboard andevents fired by the mouse.

A variable named Counter (upper-case C)

A variable named Counter (with an upper-case "C") is created, initialized to 0, and displayed in the upper-left corner of theStage area in the Scratch programming interface (see Image 1 ) . Although the label on this variable is small and difficult to read, you will see when you run this program that this is the topmost variable displayed on the Stage.

When the user clicks the green flag in the upper-right corner of the stage , the value of the variable is set to zero. Each time the userpresses the space bar, the value of the variable is increased by 1. Each time the user clicks the mouse in the blank area of the Stage, the value of thevariable is decreased by 1.

A variable named counter (lower-case c)

Another variable named counter (with a lower-case "c") is created, initialized to 0, and displayed below the Counter variable on the Stage. Again, when the user clicks the green flag in the upper-right cornerof the stage in Image 1 , the value of the variable is set to zero. Each time the user presses the space bar, the value of thisvariable is increased by 5. Each time the user clicks the mouse in the blank area of the Stage, the value of this variable is decreased by 5.

Discussion and sample code

Image 1 shows a cropped image of the Scratch programming interface for the program named Variable01 for Scratch v2.0.This image was produced by running the program online and clicking the blue button in the upper-right corner labeled See inside .

Image 1. cropped image of the scratch programming interface for the program named variable01.

Missing image.
Image 1. Cropped image of the Scratch programming interface for the program named Variable01.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
Got questions? Join the online conversation and get instant answers!
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Source:  OpenStax, Teaching beginners to code. OpenStax CNX. May 27, 2013 Download for free at http://cnx.org/content/col11498/1.20
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