Scratch on the Raspberry Pi

Issue 4 of Magpi out now. Well done with the Frogger game.

Instead of drawing a frog, why not use  the 2 scratch cat sprites? Changing the costume makes it look like he's waliking. You can call it Scratcher instead of Frogger!

Well ordered the raspberry pi and now have to wait 11 weeks! So should get it for halloween!

Just seen your article in issue 3 of Magpi.

Well done!

Hi Folks, we have too much indentation below, so I've clicked the Post Reply button rather than replying to a specific post.

Mark T wrote " I wonder if I could do something similar using the GPIO pins on the Raspberry Pi!"

The answer is, yes you can. You would need an analog to digital converter. I have been working on the Gertboard, and conveniently, it has exactly such a device. I could easily solder up something that would allow me to connect a thermistor to the A/D inputs of the the Gertboard. So then I could collect the data using a C program. And then the question is how to plot it... It has been a long time since I did anything graphical in C, does anyone by any chance have any suggestions for a good library to use to allow me to plot a graph similar to the one I made in Scratch? 

I know how to do graphics in Python (well... I'm learning Python, and I know where to look to find out how to do graphics in Python), and I have a Python GPIO module, so I could do it in Python... except that the Python GPIO module code doesn't drive the SPI bus, and the A/D chip uses the SPI bus... So I'd have to figure out how to do SPI in Python.

So I have to hand almost all the tools I need to duplicate this experiment on the Pi!

Ah, I've just thought of a way I could do it: I could collect the data using a C program, then put it into a file, then in Scratch I could read the data from the file into a list, then I could plot the data in the same way I plotted the data collected by the Picoboard! Then I could do the whole thing on the Raspberry Pi.

It would be more elegant to either (re)learn how to plot things in C, or how to drive the SPI bus in Python...

I just joined ScratchEd. I'd been looking at it for awhile, but wanting to reply to Mark T's post was what finally spurred me to join. I was going to write exactly what Mark W said. The jist of the your MagPi article is kind of "how do you do traditional CS in Scratch". Now there is a place for that (I'll tell you about some ideas I've had in a minute) but for only the second Scrach article in the MagPi, I feel that it might be a bit on the dry side. Jaseman's Dizzy Cat / Crazy Drums in Issue 1 is much more in keeping with the ... Scratch ethos (for lack of a better word).

I've been giving some Scratch lessons in my daughter's Year 4 class. The lessons were as follows:

1. Intro to Scratch, sprites, scripts, costumes, the "say" and "change costumes" blocks. I created a tiny program where the cat says "I wish I was a dinosaur", then it changes into a dino courtesy of an imported sprite, then says "Hooray!" Then I got them to do their own thing.

2. Stroytelling with Scratch. How to use backgrounds, sound, motion, and "say" to tell stories. In this case it was a ghost story. The cat is in some dark woods, along comes a ghost with a scary noise, cat screams and runs away (well, "glides" away, we haven't done animation yet). The idea of this lesson was that you have 2 or more sprites, and you have to make sure that you put the code that you want the two different sprites to execute in the scripts for those different sprites. This is something that some of the kids in the first lesson were trying to do, but couldn't figure out. Again, they were let loose on the computers to do their own thing.

I have two more lessons planned, as follows:

3. Animation. I'm going to show them how to use the repeat loop, custume change, and more instrcutions to make a bat fly across the screen. My daughter has already started playing with this sort of thing at home, for example making people dance while playing cool music.

4. Question & answer, making choices. I'm going to show them a little program where the cat asks them where they want to go on holiday and how much money they have. If they have enough money then the background will change according to the holiday destination selected. Only here do they meet variables, user input, if'/then/else, and operators (<).

This is the sort of thing that I think makes a better intro to Scratch than how to do traditional CS things in Scratch.

Where the traditional CS things are really useful is in cross curricular activities, combining science and maths. For example, the Year 6s learn about some basic stats: mean, mode, median. Showing them how to implement this in Scratch is a good way to help them understand the stats themselves and how computers handle data. It's also cool to have real data that you yourself have harvested, for example using the Picoboard to record niose levels in your classroom. At least, I think... This is definitely an untested lesson plan!

Hi Mark,

I too am excited by the rpi but as yet just have it running in a virtual machine. For me the hardware add-ons will be key and would hope that things like Lego Wedo will be supported on the Scratch port for rpi.

I liked your examples very much however am worried that you want to focus on traditional programming skills using Scratch. I don't believe Scratch is the correct tool for that. For me the whole point of Scratch is the lack of a command line and focus on multimedia to ease and engage the learning process for children. I think a Scratch "Hello World!" program should be spinning and whirling coloured letters shooting around the screen accompanied by a fanfare of trumpets!

Good luck with the article,

Mark

Hi Mark,

Thank you so much for sharing this information. I'm looking forward to buy a Raspberry Pi this year; first time hearing about the MagPi Magazine so I started to download the two (2) available issues.

I think your focus it's unique and it's fair to have variety.

Awesome examples with comments included and of course the "Hello World!" was necessary!

Hope to see more coming.

Carlos.