Skip to Content

How do you explain parallelism and events?

« Teaching with Scratch
10 replies [Last post]
Karen Brennan

We're exploring a variety of computational concepts at the Creative Computing workshop. Today we've been exploring the ideas of parallelism and events.

How would you explain these two concepts?

Eric Traub

An event is an occurrence which can be used to trigger the start of a stack of blocks.  An event can be a generated by a Broadcast, but it can also be generated by user input such as pressing a key or clicking the mouse. 

Damian DeMarco

Parallelism is a concept that has rocked me to my programming core. Having coded in COBOL and event driven programming languages and being a very strong mono-tasker by nature I like controlling ONE THING at a time.

My world is now filled with complication.


Parallelism is some "thing" happening at the same time.  Each coded script allows for this to occur using the applicable code fragments. These coded scripts can be grouped as stacks which allow the script's execution to be faster. The event is letting the "thing" know that something is going to happen. The broadcast code allows all sprites to hear the message. Then the command "when I receive" can be used to allow another happening.

This is a very exciting approach to coding.  I can envision my computer science newbies beginning their year with Scratch.  This code sets the stage for the logical thinking process needed to tackle other programming languages.

Susan Wright

In today's lesson you explained parallelism to us as "stuff happening at the same time", and events as "letting things know that something is going to happen".

I thought the lesson was brilliant--the human sprites and the taping of code to the white board slowed everything down and made important concepts really clear.  Stepping through and showing mistakes that one might make was also important.

The timing of the lesson was also perfect for my needs--I had struggled with parallelism the evening before as I was working on some projects. 




Jennifer Kilroy

Parallelism is "stuff" happening at the same time.  Using Scratch in a computer science course for a cross curriculum based project is an example of parallelism in the classroom. 

Today's example of demonstrating parallelism in programming with Scratch was a great tool for my "teacher tool box".  THANK YOU!

Jeanne Bergeron

 Events are happenings or scripts that are going to happen.

Parallelisms are events that occur at the same time, independently or in conjunction.

The modeling of these concepts this morning was great. I am such a visual learning and the large scale model help it all to make sense.

Please post those blocks as a downloadable resource. I can see using these in groups within the classroom/lab setting. I want to be able to print them on cardstock to laminate and print them on magnetics to use on a whiteboard.

Vicki Wright

Parallelism is things occuring at the same time. Your demonstration having one person being the programmer and then having other people being the sprites was very illustrative to me. I plan to use this with my students to show them how the scripts work. I love that you enlarged the commands and had them taped to the board. I was not aware that you could put scripts beside each to run parallel. The broadcast command is awesome. 

Your demonstration also clearly illustrated events - which can be defined as actions, something happening. When designing scratch projects this concept is key to building projects that perform in the manner that you want.

Hans Batra

Parallelism are events that can happen at the same time, either independently or inter-dependently.  In Scratch, each sprite can respond differently to a common event (broadcast).  They can also send messages (boadcasts) to each other to trigger new events. This can be used to control timing/coordination between sprites.  This is better than using delays (wait) which are static and are difficult to maintain when making changes to the project....

Anne Marie Wyman

Parallelism is when actions occur at the same time. When scripts in scratch are executed at the same time. You can run parallel actions in scratch by using the same "hat command" to begin each script.


Events are actions that occur in a sequence, one after another. One event can lead to another event. In scratch to use events you can use one script that continues with multiple commands. You can also use the broadcast command to control the events.

Joan Gallinaro

I loved the display of paralell events in scratch. I was not aware that we could have scripts running together but not connected, so to speak. That was very helpful to design or create the scripts "next" to each other and have them occur simaltaneously or soon after an event!


So parallelism is when things are happening at the same time and events are things that are going to be happening.