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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 installed Scratch on your computer and you have worked through all 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 case you skipped the section titled An overview of computer programming , you still might want to go back and review the section on Variables .

The Scratch program named Variable01 .sb

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

Prior to the release of Scratch version 1.4, only numeric variables were allowed inScratch. However, according to the Scratch 1.4 Release Notes , variables can now contain strings of characters. Experimentation indicates that they can also contain the boolean values of True and False (or possibly strings that represent boolean values). The previous Numbers button has been replaced by an Operators button (see Image 2 ) because it now contains blocks for manipulating strings.

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

A variable named Counter (with an upper-case "C") is created, initialized to 0, and displayed in the upper-left corner of the Stage area in the Scratch user interface (see Image 1 ) . When the user clicks the green flag in the upper-right corner of Image 1 , the value of the variable is set to zero. Each time the user presses the space bar, the value of the variable is increased by 1. Each timethe user clicks the mouse in the blank area of the Stage, the value of the variable is decreased by 1.

A variable named counter

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 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 greatly reduced image of the Scratch user interface for the program named Variable01 for Scratch version 1.4.

Image 1. a reduced image of the scratch user interface for the program named variable01.

Missing image.
Image 1. A reduced image of the Scratch user interface for the program named Variable01.

You probably can't read any of the text in Image 1 . The image is presented here solely to provide an overview of the user interface. I will provide additional (more readable) images later that show and discuss the separate parts of the user interface.

No sprites

There are a few things that we can deduce by viewing the reduced image in Image 1 . First, note that there are no sprites in this program. The program consists solely of

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
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.
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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