[squeakland] [Squeakland News] How to do timing in Etoys?

Rita ritafreudenberg at googlemail.com
Thu Sep 4 09:32:27 EDT 2014

I just got this question from my students and I thought there might be  
others with similar interests. So how can I control sequences of actions  
over time? Say, I want to use speech bubbles to tell a story. I have a  
number of sentences to show, one after another, and I want to let some time  
pass between them to give the reader time to read. How can I do that?

Well, I can build a timer and check the time to trigger actions when a  
certain time is reached. How can I build a timer?

First of all, you need a variable to count time steps. Open the viewer for  
your object. Create a variable by clicking the "v" - symbol in the top row  
of the viewer and give your variable a name. I choose "seconds". The  
default type is "Number", which is fine and 0 decimals places are perfect  
as well.

Now open a new empty script and drag the tiles to assign a new value to  
your variable into the script. Change the operation to "increase by" and  
the number to "1". Make sure the value of your variable is "0" at the  
start! Name the script "timer".

You do know already that the script, once started, will be executed  
repeatedly until it is being stopped, right? Do you also know how fast or  
how slowly this happens? You can see this when you click on the watch in  
the top row of the scriptor and hold the mouse button down. And you can  
also change it there! By default, it will be executed 8 times per second.  
Change this into once per second!

When you now start the script, each second it will increase the value of  
your variable "seconds" by 1! Now you can use the value of the variable in  
other scripts:

Use a all-scripts-tile from the supplies to start both, your script and the  
timer, at the same time and watch :)

Please note: It depends on your computer and what other programs are  
running on it at the same time, if a second in the Etoys project will be  
the same as a second at a real clock. It may not be exactly the same, but  
probably close. It is definitely good enough to control the flow of a  
story, but for scientific experiments, you should use a real timer!

You can also find a tutorial to build a timer in project 6 of the  
book "Powerful Ideas in the classroom" by Kim Rose and BJ Allen-Conn.

Von Rita am 9/04/2014 06:32:00 vorm. unter Squeakland News eingestellt
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