Advancers -Boiling Water

Introduction

This week we looked at what happens to water molecules when they are heated up.

We started with a little science experiment to demonstrate Brownian Motion, this was done with a glass of very hot water and a glass of very cold water and some ink.

When the ink is dropped in the two glasses it behaves very differently, in the cold water the ink stays suspended and visible as ink for a long time, but in the hot water the ink gets mixed into the water molecules very quickly, this is because the water molecules in the hot water are moving around much faster and bashing into the ink molecules and mixing them up.

BrownianMotion

Can you guess which glass has the cold water in?

The Plan

The plan was to build a scratch program that would  show the water molecules moving around faster or slower, depending on temperature. In order to do this we needed the following:

  • A Sprite for our water molecule
  • A slider to control the temperature
  • Some code to make them move around.

The Sprite

Water molecules are made up of 2 Hydrogen atoms and 1 Oxygen atom (H2O), the Oxygen atom is quite large compared to the Hydrogen atoms and the Hydrogen atoms stick to the Oxygen atom at about a 45 degree angle, they end up looking like Mickey Mouse, so our Sprite looked something like this:

Sprite            SpriteSettings

We changed the settings of the Clone so it didn’t rotate.

The Temperature Slider

In order top control the temperature we created a variable, making sure that it was set for “All Sprites” and that it was set to be a slider. We also set the minimum and maximum values:

TempSlider

The Code

As we needed lots of these Sprites we decided to use the Create Clone block (Control) to create 100 of them.

In order to move the Sprites around we needed to keep looping, picking a random direction and then moving a little bit. We also needed to change the amount we moved and also the direction as the temperature went up. The direction needed to be more upwards as the temperature got higher so the water molecules would start floating like steam if the temperature got high enough.

We used a Gravity variable to make sure the Sprites pointed upwards as the temperature got higher, because this needed to be different for all the Sprites so they moved in random directions, we created the Gravity variable “For this Sprite only”

The code ended up looking like this:

GreenFlagCode

 

Initialise the Temperature variable and then create 100 clones.

 

 

 

CloneCode

 

Initialise the Sprites Gravity variable

Pick a random spot along the bottom of the Stage

Make sure we are pointing more towards the top, depending on the temperature.

 

 

If the temperature is > -1 move around, otherwise we are frozen, so just go back to the bottom of the screen.

 

 

Notes:

The project that we built is available on the Scratch Web Site:

User Name : cdadvancers1819
Password : advancers

Project : Class-BoilingWater

Remember, you can put your own projects up there as well if you want.

 

 

 

 

Advancers – Gravity

Introduction

This week we decided to create a Lunar Lander game that demonstrated the effects of Gravity.

The Plan

As always we started with a plan:

  1. A Spaceship Sprite with 4 Costumes
    1. No power
    2. Up Rocket firing
    3. Left Rocket firing
    4. Right Rocket firing
  2. Buttons to control the Space Ship
  3. Stage which should be a picture of the moon.
  4. A landing pad to land on – just draw on the Stage
  5. Code to control the Space Ship
    1. 3 Variables, to store Gravity, Power and LeftRight information.

Space Ship Sprite

This what mine looked like:

SpaceShipSprite

Space Ship Sprite

 

 

 

The Left and Right costumes can be confusing, to move left, the flame needs to come out of the right, and to move right the flame needs to come out of the left hand side.

 

 

 

 

 

 

Stage

My Stage looked like this:

Stage

 

One thing to remember is to have the landing pad in a different colour.

Buttons and Code

I’ll put these 2 parts of the plan together as it makes more sense.

We decided to use 3 different buttons to control the Space Ship

  1. Up Arrow – This would fire the rocket at the bottom of the Space Ship
  2. Left Arrow – This would fire the rocket on the right side of the Space Ship
  3. Right Arrow – This would fire the rocket on the left side of the Space Ship

And now the code.

We needed code for each of the buttons, code to move the Space Ship and code to know when we have landed. This meant we had lots of small pieces of code all running together in Green Flags with forever loops.

We also decided that we would need 3 variables to store information so we could work out how far to move the Space Ship.

  1. Gravity – This would change as the Space Ship got higher, just as real gravity does.
  2. Power – This would change when the Up arrow was pressed and also when nothing was happening
  3. LeftRight – This would change when the left or right arrows were pressed

And don’t forget if we have variables, we should set them to starting values when the Green Flag is clicked.

Initialise

 

This also has the code that puts the Space Ship in to a starting position. Note the Y value as this is used later in the code to see if we are on the ground or not.

 

For example, when the one of the left or right arrow keys was pressed we would change the Costume and change the LeftRight variable.

RightArrow

 

We did the same for the left arrow. Note that we just add (or subtract for the left arrow) a small amount from the LeftRight variable.

The delay is to make sure that the variable is not updated too fast if the arrow button is held down.

 

For the Up arrow we have to change a different variable

UpArrow

 

Note the wait is much shorter, this is to match the wait in the forever loop that moves the Sprite.

We also change the Power variable by a large amount as this helps with the calculations.

 

Once we had the buttons working we could move on to the Code that moved the Sprite.

The Left or Right movements were easy, that would just be the amount in the LeftRight variable.

The Up or Down movements were a little trickier as we had to account for Gravity as well. So we just used the Y position of the Sprite and added 180 (to make it a positive number). This meant that Gravity changed as the Sprite moved up or down, which is exactly how Gravity works in real life.

This is how the code ended up

MainForeverLoop

 

We move first and then check how high we are.

If we are above the ground, we know this by checking that we are above the starting position of the Sprite, then we adjust Gravity and adjust the Power down.

Note the wait is the same as the Up Arrow code.

Also, if we are on the ground, we set Gravity and Power to 0.

 

 

There was one final piece of code that we didn’t do but I have added here, this was to check if we had landed and if we had, display a message and end.

It was just another Green Flag with a Forever loop and we kept checking to see if we were touching the colour of the landing pad.

Landing

 

Not much here, but might be better if there was a wait as well.

 

 

 

Finally, if you want to see all the code in one go, here it is

AllCode

Notes:

The project that we built is available on the Scratch Web Site:

User Name : cdadvancers1819
Password : advancers

Project : Class-Gravity

Remember, you can put your own projects up there as well if you want.

Creators – Pattern

washer-machine-porous-mechanical-83852

This week we looked at two important concepts, loops and lists.

Loops

Start by imagining we wanted to draw four circles next to each other. We could write four calls the ellipse function, like this:

let size = 50;

ellipse(25, 25, size, size);
ellipse(75, 25, size, size);
ellipse(125, 25, size, size);
ellipse(175, 25, size, size);

Pretty easy. What if we had variables for the positions? We’d get this:

let size = 50;
let x = size / 2;
ley y = size / 2;

ellipse(x, y, size, size);
x = x + size;
ellipse(x, y, size, size);
x = x + size;
ellipse(x, y, size, size);
x = x + size;
ellipse(x, y, size, size);
x = x + size;

It’s longer than before, but notice how the same two lines now keep repeating. If we had a way to say “do these two lines four times” then this would get much shorter, and we do. We use the for statement:

let size = 50;
let x = size / 2;
ley y = size / 2;

for (let i = 0; i < 4; i++){
  ellipse(x, y, size, size);
  x = x + size;
}

The for statement is a bit complicated, so let’s break it down:

for (do first; check to see if we keep going; do every time 2) {
  do every time 1
}

Note the curly brackets (braces) containing the stuff we want repeated.

So in our case we:

  1. First create a new variable called i and give it the value 0
  2. Check to make sure that i is less than 4
  3. Draw our ellipse and make x bigger
  4. Increase i by 1
  5. Go back to step 2 and check if we can keep going, otherwise stop

This means that i will have the values 0, 1, 2 and 3 and our two lines will be run four times in total. Result! Our code can draw a row of circles. If we increase the value in the check, we can have as many as we like. We choose to have 8.

Nested Loops

Nesting a loop means putting one loop inside another. What’s the point of that? Well in our case we have a loop that can draw a single row of circles. If we put all of that inside another loop we could draw several rows. The row outside has a different variable j and also runs eight times. After we draw our row we do two things:

  1. We make y bigger move down the screen
  2. We move x back to the left to its starting position for the next row

The code now looks like this:

let size = 50;
let x = size / 2;
let y = size / 2;

for (let j = 0; j < 8; j++){
  for (let i = 0; i < 8; i++){
    ellipse(x, y, size, size);
    x = x + size;
  }
  y = y + size; // Move down and
  x = size / 2; // Back to the left
}

We now have 8 x 8 = 64 circles in a grid.

Changing the Colour of Some Circles Based on a Check

We then added code just before our call to ellipse() to change the colour based on some check:

if( /* some check here */ ){
  fill("red");
}
else {
  fill("white");
}

We experimented with some different checks to see what might happen. This check turns the upper-left of the grid red:

if (i + j < 8 ){ 
  :  :  :

This check, using the modulus operator, turns every third circle of the grid red:

if ((i + j) % 3 == 0){ 
  :  :  :

This check paints a red cross through the centre of the grid:

if (i == 3 || i == 4 || j == 3 || j == 4){ 
  :  :  :

Lists

We then jumped quickly into lists. Also called arrays, lists are like a variable that can store several values. We create them simply like this:

let a = []; // An empty list
let b = [1, 2, 4, 7]; // A list created with four entries

To get at the entries in a list you just use the list variable’s name and square brackets containing the number of the entry in the list you want to get out, noting that the first one is zero:

b[0] = 10; // Set the first entry in the list to ten
b[4] = 301; // Set the fifth entry in the list to three hundred and one

A list isn’t just for holding numbers though, it can hold anything. It can hold strings for example, or even other lists!

It’s this idea of holding lists that we use to define our pattern.

Defining our Pattern

We make a list with eight entries, each of which is a list also containing eight entries, all zero. We write it so it forms a neat block like this:

let pattern = [
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0]
];

Then down in our code, where we’re deciding what colour to make our circles, we change the check to read:

if (pattern[j][i] == 1){  
  : : :

What does this mean? Well, j is a counter that goes from 0 -> 7 as we go down our eight rows. Given that, pattern[j] means get entry from our list for that row. Since pattern[j] is a list too, we need to say which entry we want in. The variable i goes from 0 -> 7 as we go across each row. So, pattern[j][i] gets the list for the row and then picks out the number for that column.

Once it’s set up, we can then change zeros to one in our pattern and have our circles turn red to match (red in the text below to make them stand out):

let pattern = [
  [0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 1, 0, 0, 1, 0, 0],
  [0, 0, 1, 0, 1, 0, 0, 0],
  [0, 0, 1, 1, 0, 0, 0, 0],
  [0, 0, 1, 1, 0, 0, 0, 0],
  [0, 0, 1, 0, 1, 0, 0, 0],
  [0, 0, 1, 0, 0, 1, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0]
];

Screenshot 2018-10-15 at 18.14.34

We have essentially built something that works like an image file! Our pattern is the image data and our program is the code that draws it.

As several smart people already noticed, you’re not limited to one and zero. By using more numbers, and expanding the if statement, you can have as many colours as you like.

Download

The files for this week are on our GitHub, as always.

Explorers Week 5 – Help Bo Peep find her sheep

Hi everyone,

Thanks for coming Saturday even though the weather was dreadful.

This week, I helped Bo Peep found her sheep! Some of you did the same and some used ideas like Minecraft Steve finding Iron Ore and Diamonds, Knights finding dragons or a Princess finding flowers.

Before we even started our game this week we talked a little bit about File Management and about the importance of keeping your files somewhere you can access them quickly and giving them a meaningful name.

So to this end, we all created a folder where we will be keeping our files in the future and within that we had a sub folder for this weeks files.

We started our game by drawing our background on our stage:

Unfortunately, due to internet problems we could not search the internet for images for our Sprites, but we could still use the sprites from the Scratch Library.

This week, we decided to move our main sprite using the arrow keys. For this we had to learn a small bit about the X and Y axis and I gave you a little tip on how to remember which is which!

Hope you all enjoyed this week, aee you next week when we will be starting a new game!

Here are the notes for this weeks session in PDF CDA-S7-Week_05-BoBeep.pdf

Martha

Julie, Ruaidhrí and Eoin

 

Explorers – Week 4 – 2018, Improving Our Game!

Hi everyone,

Thank you do everyone you came along on such a lovely day on Saturday, hope you all got to go outside when you went home and enjoyed the weather.

This week, we improved on our game from last week.

Most games reward us for achievements (Gaining:Scores/Money/Health) and penalise us for making mistakes (Losing:Lives, Health, Money)

To this we had to create a Variable. Remember my box with the blocks. A variable holds information for you that you can use again. Remember to always give it a name that is meaningful….

Everything we have learned so far we will be using in ,most of our games we will make in future sessions. Don’t worry if you didn’t understand everything, we will be going over it again and again.

Have fun with the code you have done. Maybe try making another game!

Here are the notes from last week in PDF CDA-S7-Week_04-FirstGame-Part2.pdf

See you all next week

Martha & Julie, Ruaidhrí and Eoin

Hackers – Temperature Control, Part 1

IMG_20180929_131406

In Hackers, we started work on a short project for a temperature-controlled soldering station. As shown on the whiteboard above, the basic idea is:

  • A temperature sensor is connected to an Arduino (analog input)
  • A soldering iron, with its tip located near the sensor, is wired to the mains via a relay switch
  • The Arduino can control the relay switch to turn the soldering iron on/off
  • This is the basis for a simple bang-bang controller: we have a target temperature (e.g. 200 degrees) and a tolerance (e.g. ±10 degrees), then you turn it on if the temperature is below 190 degrees and turn it off if above 210 degrees.

We noted that since there will be space between the soldering iron tip and the temperature sensor, the temperature it will read will be lower than the tip temperature.

As the whiteboard shows, this project also involved discussion of: wiring for the thermocouple; how breadboards are wired; normally-open vs normally-closed relay switches.

One group used a LM35 temperature sensor – here are its specs, and the group found it interesting to see how detailed and useful these data sheets are: http://www.ti.com/product/LM35

The other group used a potentiometer to simulate temperature, so they could test it working over its full range, as shown here:

IMG_20180929_135713

Below is the code for reading and displaying the temperature. Next steps will be to integrate it with the relay.


// Michael Madden, CoderDojo Athenry
// Reading a temperature sensor.

// The temperature sensor is an LM35 - here are its specs: http://www.ti.com/product/LM35 
// THe temperature range is -55 to 150 degrees celcius.
// Its output voltage pin is connected to an analog input on the Arduino (A1),
// from which we read a value in the range 0-1023, so we convert them.

void setup() {
  // Just needed for print statements to work
  Serial.begin(9600);
}

void loop() {
  // Read the temperature sensor: get a value in range 0-1023
  int val = analogRead(A1);

  // From the analog input, we get a value in the range 0-1023
  // and we need to convert it to a temperature in the range -55 to 150 degrees.
  // The two lines below achieve this in differnet ways and give the same result.
  int temp1 = (val/1023.0)*205 - 55;
  int temp2 = map(val, 0, 1023, -55, 150);

  // Print out the raw value and converted temperature
  Serial.print("Sensor value = ");
  Serial.print(val);
  Serial.print("\tTemperature 1 = "); 
  Serial.print(temp1);
  Serial.print("\tTemperature 2 = ");
  Serial.println(temp2);

  // Wait 100 milliseconds before reading the sensor again
  delay(1000);
}

 

Bodgers – Making For The International Space Station

Hello again everybody.
This week in the Bodgers group we started working on our code for the Mission Zero Challenge.

mission-zero-logo

We began by writing a simple text message on the 8×8 full-colour LED display, then we changed the text and background colours. We then coded a picture by assigning a colour to each of the 64 LEDs on the display. We finished the session by taking a quick look at using the temperature sensor to read the temperature. Here are my slides from this week day 2.
Next week we will recap what we covered this week and we will start to personalise our code for the challenge.

In the meantime, here’s a couple of fun videos on how the Astro Pi computers got to the ISS.

See you all next Saturday

Declan, Dave and Alaidh

Explorers – Week 3 – 2018, Your First Game!

Hi everyone!

Wow! what a fantastic turnout on Saturday again, 79 ninjas in the room! plus a few adults!

I hope you had a good time, I know that I really enjoyed it. There was a really great atmosphere and energy in the room.

A special thank you to Mentor Julia for getting 14 loaner laptops working for us this week, so that everyone that wanted to participate, could. Another thank you to the other Mentors in the room, Eoin and Ruaidhrí, it makes my job easy when they can get around the room and help out when needed. You are doing a great job.

One of the first things we must do before we start anything is make a plan.


We quickly learn when we begin our coding that it is very important to test our code as we go along. Making mistakes is good, but we must learn from them by spotting them (testing) and fixing them.

I am attaching my notes in PDF for you. CDA-S7 Week_03-FeedingtheFish.pdf

We will continue to add to the game next week but don’t worry if you weren’t here this week, I will have a copy of the game so that you can join in.

See you all nest week!

Martha and the Explorers Mentors, Julia, Eoin and Ruaidhrí