S4A (Scratch for Arduino) Project - A Keyboard Controlled Robot Car

A fun project to create a keyboard controlled robot car... based on the "Robotics: keyboard driven car" project on the S4A site. This to me, is a perfect example of an interdisciplinary project: there is quite a bit of mechanical, electrical and computer engineering involved. This project is being used by the Grade 5 kids in my child's school this year; the kids have been working with the Pro-Bot for quite a bit of time and I felt that letting them create their own robot car that behaves similar to the Pro-Bot is a great finale. So far, it's my favorite Arduino project. Below is a formal lesson plan for the robot car.

Note: This is a simplified version of the car from the S4A site - it just involves creating the keyboard driven car, minus the remote controller. This means the car stays connected to the laptop via the USB cable.

S4A (Scratch for Arduino) Project - A Math Game using LEDs: Version 2, with a Single Sprite

Here is a much simpler version of the previous Math Game using LEDs: The aim is to design an interactive Math video game, where you ask questions and if your answer is right, an LED lights up. In the previous version, you had two sprites that communicate with each other, checking the values of variables. In this much simpler version, there is just a single sprite - the Arduino sprite itself, that asks questions and checks the answers for correctness. This version takes away any complication involved in maintaining a communication channel between the sprites, and is probably the easiest way to start off. The following is a formal lesson plan for the same; a set of slides are also provided. The assignment is intended for students in Grade 5 and higher.

Aim

A gentle introduction to the Arduino hardware, with S4A (Scratch for Arduino) as the IDE.

Objective

Introduce the students to the Arduino platform, via a simple project to light up an LED. The students use their knowledge of reactive programming & conditionals

A Formal Lesson Plan for the Scratch Food Chain

Here is a formal lesson plan that I designed for our Grade 5 students, to create an animated representation of a food chain. I have previously published a Scratch project for a food chain: A Food Chain in the Northern Temperate Forest. The lesson plan below is intended to help the instructor introduce the project in the classroom step by step, so that the students can learn the logic involved and gain familiarity with the Scratch instruction set. Food chains are part of the Grade 5 Science Standards, and this project could easily evolve into a presentation by the students at the end of the session.

A Pong Game - programmed with Scratch

Different versions of the ever popular Pong game are available on Scratch. Here’s the link from ScratchEd: http://scratched.gse.harvard.edu/sites/default/files/scratch-lesson-7-the-pong-game.pdf. The following lesson plan using Scratch is one that I created for our Grade 5 students, taking inspiration from this sample code for Pong.

Given the code for an interactive Pong video game, the students edit the program to create multiple versions of the game with varying difficulty levels. The aim is to gain familiarity with the Scratch software platform and learn how to create games/ programs that involve user interaction. The students learn to modify the various facets of the code, and in the process learn about reactive programming, conditionals, loops, sprites, backgrounds and variables. They discuss how the variables in the given program can be used to model the different factors (forces, energy, orientation, type of materials, etc.) involved in the movements of a bouncing ball.

Platform

We use the S4A (Scratch for Arduino) platform for the Grade 5 students in our school. This project is intended to provide an introduction to this software platform before the kids start using it as the IDE for Arduino. S4A is based on Scratch from MIT and is quite similar to it. Note that in this particular assignment, we do not use the Arduino.

The sample code for Pong can be found in the Examples/Games folder in S4A.

Computer Science Concepts

Reactive programing

Forever loops

Conditionals

Common Core Standards

Math Standards:

• Variables
• Angular measurements
• Coordinate geometry for a 2D plane

NGSS Science Standards:

• Forces & interactions involved in a bouncing ball

The Lesson Plan

The aim is to learn about the basics of the Scratch/S4A platform in this assignment:

• open, edit, save & close a project
• sprites & backgrounds
• the Scratch instruction set

The students read the given code and understand the various programming components that are involved in the design of the game. The factors that affect the movement of the pong ball are included as variables in the code. Students learn how modifying them can change the way the game is designed. The difficulty level of the game can be altered by modifying the variables. A discussion on how the variables in the program represent the different factors (forces, energy, orientation, type of materials, etc.) that govern the movement of the pong ball can round up the class.

This assignment also provides a first hand look at the use of conditionals and forever loops. Reactive programming, where the sprites react to various key presses or mouse movement is also learned.

Slides

I put together a set of slides for this lesson as I felt that it might be easier for the kids to tag along with the lecture, by programming on their computers. They can store the different versions of their program under different file names. 

The Pong Game PPT

Programming Assignment

Modify the code for the sprites to create different versions of the game, as suggested below.

Paddle Sprite:

The code for the Paddle Sprite in the sample code is designed to follow the mouse/cursor horizontally.

1. Can you modify the code for the Paddle Sprite so that it follows the mouse pointer vertically on the screen?
2. Modify the code for the Paddle Sprite so that it follows the mouse pointer everywhere on the screen.

Ball Sprite:

Try experimenting with different values for the variables. Note the changes you see each time.

1. Use the “pen down” instruction to track the path of the ball.
2. Would the game ever take off if the starting position has the ball touching the red zone on the background?
3. Guess why the “forever loop” is used in the game.
4. Guess why the “180 - direction” is used to set the direction of the ball when it hits the paddle.
5. Guess what the “turn random angle” does. Experiment with it to increase the difficulty level of the game.
6. Can you make the ball move faster at the start of the game by changing one of the variables?
7. Can you make the ball move faster when it hits the paddle by changing one of the variables?
8. Increase the difficulty level of the game by increasing the speed & randomness of the ball.

Challenge

1. Introduce a variable to keep track of scores - you start with zero points & every time the paddle hits the ball, you get a point.
2. Can you program the paddle to be moved on the screen using the arrow keys on the keyboard, instead of the cursor?

Summary

Summarize the lesson by going over what some of the variables in the game represent. Here are a few examples:

1. When you change the speed of the ball, what does it imply about the loss/transfer of energy?
2. If the ball moves faster after hitting the paddle, what kind of material could the paddle be made of? Is it one that absorbs much of the ball’s energy?
3. The red background in the sample code makes the ball come to rest completely. Discuss the energy transfer of the ball in this case. What materials could possibly have made the pong ball come to rest on coming into contact with it?

Here’s a link with more info about the science of a pong ball, if you would like to go further with the discussions.

Doodle Pencil - Using the Pen & Mouse Pointer Coordinates in Scratch

Here's a fun little Doodler made with Scratch:  The Doodle Pencil
















This was rather a spur-of-the-moment project... inspired by Etch-a-Sketch...  and kind of a follow-up on the Pac-Man game...

The code is minimal, and I feel not much of an explanation is required. The instructions are mainly from the Pen area of the Scratch Instruction Set, along with the instruction to follow the mouse-pointer. The "green flag click" handler does the initialization - clearing the screen, setting the sprite size and setting up the pen size & color.

The code is interactive, and it's designed to enable the user to lift and lower the pen as required while doodling: Move the mouse pointer to the desired location on screen and then click on the up arrow key; the pen will start drawing now by following the movements of your mouse pointer. Click on the down arrow key to stop drawing at any point.

This could be a fun little exercise for the kids to see how different combinations of the "Pen" and "Motion" instructions interact with each other.

Enjoy doodling!

CopyCat - A Simple Intro to User Input and Variables via Scratch

My child and I worked on CopyCat as a simple introduction to variables and user input in Scratch. Algebra is part of the Grade 4 Math curriculum in the USA, and this project could be a fun way to introduce the use of variables.

Aim:  

Design an interactive game in Scratch, where a CopyCat copies/repeats everything that you type in.

The Design Process:

• Only a single sprite is required: the CopyCat. You can either choose from the list of sprites already available on Scratch, or draw your own. 

• To provide user interaction in starting and stopping the game, we used the "green flag click" to start and the "space key click" to stop the game (both of which can be found under the section "Events" in the Scripts area in Scratch). You can choose any of the options that are available in "Events" to do the same.

Various sections in the Scripts area of Scratch

And now the fun part: CopyCat needs to copy everything that you type in.
How can we achieve this?

• Under "Sensing" in the Scripts area in Scratch, you will find a block that asks for user input and waits for it. This is what we shall use, to ask the user to type in anything they like.

• Once the user input is received, CopyCat needs to repeat it. But, how can CopyCat remember what the user typed in? Here is where the concept of variables comes into play. In the section "Sensing", you will find the variable "answer", which stores whatever the user typed in. 

• I recommend selecting the box right next to "answer", so that it is visible on the screen and the kids can see how its value varies (hence the name variable), depending on the user input.

• The CopyCat can now use this variable along with the "say" instruction (found in the "Looks" area of Scripts in Scratch), to repeat/copy whatever the user types in.

Ask the students to try writing the code upto this point:

1. When "green flag clicked" (or other event), CopyCat asks the user to type in something.
2. CopyCat repeats the user input, via the variable "answer". 
3. When "space key clicked" (or other event), stop the program.

Let the students experiment with different values for the user input and observe how the variable changes accordingly. Once comfortable with the use of the variable, they can hide it by deselecting the box next to "answer".  It would be good to remind the students at this point, that this feature is helpful for debugging.

Here are three screen shots to demonstrate how the user input gets stored in the variable "answer".

  Asking for user input; variable is empty

User input entered; variable is empty till Return key is pressed

User input is now stored in the variable

Pac-Man is Chasing my Planet!

My child's class was recently introduced to Cartesian coordinates in Math. And in our coding class, we have been practicing interactive programming for the last few weeks. So, I thought of putting together a very simple template that  combines both the concepts, that the kids could then remix...  Pac-Man is Chasing my Planet! was the result... took me less than 10 minutes to put together and the kids loved it.

We went through the Pac-Man template code as a group & discussed the use of the XY coordinates. I showed the kids how the XY coordinates displayed under the Scratch animations area change, as I move the cursor around on the screen. Our discussion then proceeded along the following lines:

• If I wanted my sprite (the planet, in this case) to move anywhere the cursor moves, what values should I use for the sprite's X and Y coordinates? 
• The above point was also a good place to talk about variables, and how the change of the cursor position is always reflected in the planet's position. 
• Should I move the planet around for just a few times or all the time? What kind of a loop should I use here?
• How can I make Pac-Man always follow the planet? Which loop should I use? 
• What values should I use for Pac-Man's X and Y coordinates? 
• Here, the kids quickly saw that without a small degree of separation between the coordinate values of the planet & Pac-Man, the two sprites overlap each other.
• BTW, the "if-else" clause was purely optional, for those to wanted to add another level to their game. The majority went with just a "go to x() y()"
• And finally, the interactive part of the game... I put in the requirement that there should "a key press" or "the green flag click" to make the game start, and something similar to end the game. 

In the next one hour, the children came up with multiple variations of the game, making their own sprites and designing various versions of tag... All in all, a very fun class for them and me to wrap up the school year.

Happy Summer!!

A Food Chain: Made from Scratch

Here is a Scratch project that my 9-year-old put together, depicting a Food Chain in the Northern Temperate Forests. An avid lover of animals, this project combining learning in two areas, was a very fun one for him. I loved the fact that he could create a presentation about an ecosystem, while combining his learning with art, storytelling and programming. A good example of an interdisciplinary project...

This project took him a few weeks to create, including the time for the initial research about the ecosystem. We went through the project in small steps, designing the various stages... deciding on the characters in the food chain, the order in which they appear, special effects if any, etc. As you can see from the progression along the length of the project, more special effects started appearing as he learned more about creating animations.

Major learnings for my child were:

• Using "show" and "hide" instructions to make characters appear and disappear in the story.
• Timing -- using the wait statement and figuring out how long to wait, before each sprite makes its appearance on screen.
• Animation: Creating multiple costumes for a sprite and alternating between them to create the effect of movement.
• Changing the size of a sprite to create the visual effect of distance.
• Creating and using different backdrops at various points to create the effect of multiple scenes.
• Using XY coordinates to decide on positions of the sprite at various points of the presentation.

Note:

This project simulating a food chain, could potentially be a Grade 5 class project. Food chains are part of the Grade 5 syllabus; the description can be found here on the NGSS (Next Generation Science Standards) website. The students are expected to  "develop an understanding of the idea that plants get the materials they need for growth chiefly from air and water. Using models, students can describe the movement of matter among plants, animals, decomposers, and the environment and that energy in animals’ food was once energy from the sun".

Traveling Pro-Bot: Finding the shortest path

The Traveling Salesman Problem is one of the most famous and one of the most complex in Computer Science. The problem can be cited as the following: Given a list of cities and the distances between each pair of cities, what is the shortest possible route that visits each city exactly once and returns to the starting city? 

This problem in its various forms has a variety of applications in multiple fields for optimization purposes. For example, a school district would like to find the best route for a school bus to pick up kids in the morning. The courier company would like to determine the best route to drop off packages, with minimum fuel costs. In a factory assembly line, if you can find a way to visit all the required stations in minimal time, you can manufacture more units in a day. There are several more instances of the application of this problem and the “cities” in the original problem will denote various points in those instances. As the number of “cities” increases, the complexity of the problem also increases.

We shall work on a very simple instance of the above problem, involving a maximum of just 5 cities. Pro-Bot shall represent our salesman, driving between the various cities.

Computer Science concepts involved:  Sequential programming, A peek into optimization techniques

Math concepts involved:  Using data given for creating a graph, Measuring distances and directions on a map, Finding shortest path, Cost comparison, Measuring angles, Scaling quantities 

Grade levels:  4, 5

Hours required:   2 or more

Distance between cities in miles
The distances between the various cities are given in the table below in miles. Note that these are straight line distances between the cities (as the crow flies) and not driving distances. 

                     City Name                            City Name                      Distance in miles

On a map of USA, locate the various cities given in the table above. 

Task 1
We shall start with a very simple route. Let’s consider the three cities of San Diego, Austin and Denver. Pro-Bot has to visit all three cities, starting from San Diego and returning to San Diego. No city other than San Diego should be visited more than once. What order should the cities be visited in so that the total distance traveled is minimized?

Remember that the minimum distance Pro-Bot can draw is 1cm. Given the distances in the table above and using a scale of 1 cm to represent 100 miles, can you round the distances so that they can be used by Pro-Bot?  Draw a small graphical representation of your cities and distances between them as shown below. This might be helpful for you to visualize the problem. 

Using  a map of the USA and a protractor, try to find out the angular measurements between the various cities (approximate values are fine). Using the distance and angular information, as well as the location of the various cities on the map, can you write a program for Pro-Bot to visit all three cities, starting and ending at San Diego?

If gas costs $3 a gallon and Pro-Bot uses one gallon per 10 miles, how much did it cost for the trip?

Task 2
We shall move on to a route that involves 4 cities now: San Diego, Austin, Denver and Chicago. Pro-Bot has to visit all four cities, starting from San Diego and returning to San Diego. No city other than San Diego should be visited more than once. What order should the cities be visited in so that the total distance traveled by Pro-Bot is minimized? 

Remember that the minimum distance Pro-Bot can draw is 1cm. Given the distances in the table above and using a scale of 1 cm to represent 100 miles, can you round the distances so that they can be used by Pro-Bot?  Draw a small graphical representation of your cities and distances between them as we did in the previous task. This might be helpful to visualize the problem.

Using  a map of the USA and a protractor, try to find out the angular measurements between the various cities (approximate values are fine). Using the distance and angular information, as well as the location of the various cities on the map, can you write a program for Pro-Bot to visit all four cities, starting and ending at San Diego, so that the total distance traveled is kept to a minimum?

If gas costs $3 a gallon and Pro-Bot uses one gallon per 10 miles, how much did it cost for the trip?

Task 3
We shall work on a route that involves 5 cities now: San Diego, Austin, Denver, Chicago and Las Vegas. Pro-Bot has to visit all five cities, starting from San Diego and returning to San Diego. No city other than San Diego should be visited more than once. What order should the cities be visited in so that the total distance traveled by Pro-Bot is minimized? 

Remember that the minimum distance Pro-Bot can draw is 1cm. Given the distances in the table above and using a scale of 1 cm to represent 100 miles, can you round the distances so that they can be used by Pro-Bot?  

Using  a map of the USA and a protractor, try to find out the angular measurements between the various cities (approximate values are fine). Using the distance and angular information, as well as the location of the various cities on the map, can you write a program for Pro-Bot to visit all four cities, starting and ending at San Diego, so that the total distance traveled can be kept to a minimum?

If gas costs $3 a gallon and Pro-Bot uses one gallon per 10 miles, how much did it cost for the trip?

A few points to think about:

• As you worked on the above 3 tasks, did you notice that as the number of cities increased, your job of finding the route with minimum cost also became more complex?
• Was there a particular technique that you used for finding the  minimum cost route in each case? 
• Or did you evaluate all possible routes in each task and then choose the best one to write your program for? Do you think that it would be a good solution for a large number of cities, say 1000 or 10,000 or so?
• Can a change in constraints lead to a change in the routes that you found? Check the next section for an example.

A Different Condition & A Different Route:

Now, imagine that Pro-Bot is a rental car that you picked up at the San Diego airport. You shall use Pro-Bot to visit various cities starting from San Diego. We would still like to keep our distance and gas costs to a minimum and visit each city only once. But this time, Pro-Bot does not need to return to San Diego after visiting all the cities. You can it drop off at the last city that you visit. 

For each of the tasks above, does this change in the conditions cause a change in the route?

Task 4:
Pro-Bot visits San Diego, Austin and Denver, starting from San Diego. The distances between the cities and the gas prices are the same as before. You do not have to return to San Diego. Can you write a program for Pro-Bot’s route that involves the minimum gas cost? Is it the same route as in Task 1?

Task 5:
Pro-Bot visits San Diego, Austin, Denver and Chicago, starting from San Diego. The distances between the cities and the gas prices are the same as before. You do not have to return to San Diego. Can you write a program for Pro-Bot’s route that involves the minimum gas cost? Is it the same route as in Task 2?

Task 6:
Pro-Bot visits San Diego, Austin, Denver, Chicago and Las Vegas, starting from San Diego. The distances between the cities and the gas prices are the same as before. You do not have to return to San Diego. Can you write a program for Pro-Bot’s route that involves the minimum gas cost? Is it the same route as in Task 3?

Nets of 3D Shapes Part 2 - Prisms & Pyramids: More Practice with Procedures using Pro-Bot

This programming assignment is intended to provide more practice with Procedures using Pro-Bot. We shall use Procedures to store programs for various polygons. We shall then write programs for Pro-Bot to draw nets of some 3-Dimensional figures using these Procedures. 

We already worked on the nets of cubes in our previous assignment,  Nets of 3D Shapes Part 1 - Cubes. This is a follow-up to that work, involving more complex polyhedrons. 

Computer Science concepts involved:   Sequential programming, Repeat loops, Procedures

Math concepts involved:   Polyhedrons (prisms, pyramids), Nets of 3D figures (visualizing 3D figures on a 2D plane, identifying multiple nets, properties of nets), Polygons (triangles, quadrilaterals, pentagons), Measurement, Angles

Material required:  Card paper/thin cardboard to draw the nets on

Extension activity:   Make the 3D figures by cutting out the net from the card paper and folding along the edges 

Grade levels:   5

Hours required:   2 or more

Nets of 3-Dimensional Figures

A 3-Dimensional (3D) shape is a shape that has length, width and depth. They are also called solid figures or solid shapes. The length, width and depth are the three dimensions. Most of the objects that we see around us are 3-Dimensional. For example: your books, school bag, a box of crayons, Pro-Bot, table, chairs, water bottle, soccer ball, even yourselves are all 3D shapes.

How do these shapes differ from 2-Dimensional (2D)  figures, like the ones that you draw on paper? Think about how a cube or a sphere differs from a square or a circle drawn on paper. Well, the difference is that they have depth, unlike the 2D figures drawn on paper, which have only length and width. 3D shapes do not lie flat on a plane surface and they are difficult to draw on a piece of paper. 

But what if we could open up the 3D shapes and lay them out flat on paper? This would show us exactly how these solid shapes are made. A net can help us convert a 3D shape to a 2D figure. Nets are the flattened shapes of 3D objects. The net shows every edge and every face of the 3D figures laid out flat on paper. The net has only length and width; it does not have depth. It makes it easier for us to study and analyze some of the properties of a 3D object. You can cut out the net from the paper and fold it along the edges to create the 3D object. The same 3D object may be flattened into more than one net.

Let’s look at a few 3D shapes and draw their nets. We shall use Pro-Bot to draw the nets on thin cardboard. You can then cut out the nets and fold them to create the 3D shapes.

Nets of Prisms:

A prism is a solid object whose bases (or ends) have the same size and shape and are parallel to each other. The sides of the prism are parallelograms. A prism has the same cross-section all along its length. The shape of the bases (or ends) give the prism its name. We shall look at two types of prisms here:

• Rectangular prisms
• Triangular prisms

Nets of Rectangular Prisms:

Rectangular prisms are very commonly seen in our daily lives; for example, boxes, books, buildings, etc. A rectangular prism has 6 rectangular faces, 12 edges and 8 vertices. Opposite faces are congruent and have the same dimensions.  All faces of the rectangular prism are rectangles. A cube is a rectangular prism where all rectangular faces have equal edges.

Given below is a rectangular prism and one of its nets. The bases of this prism are square in shape. Hence it is also called a square prism. 

1. Write a program for Pro-Bot to draw the net given in the figure. Store the program for each rectangular face as a Procedure. (If there is a procedure for the 6 cm side square that you have already written, it can be used in this program as well.) 
2. Can you come up with more nets for the above prism. Try at least one other net and write a program for Pro-Bot to draw it. 
3. Once you are done drawing each net using the Pro-Bot, cut out the net from the paper. You can fold the paper along the edges and create the prism.
4. Given below is another rectangular prism. Write a program for Pro-Bot to draw a net for this prism. 

  

Nets of a Triangular Prism:

In the figure below, you can see a triangular prism, with a shape that resembles a camping tent. It has 5 faces, two of which are equilateral triangles and three are rectangles. 

1. Write a program for Pro-Bot to draw an equilateral triangle of sides 6 cm and store it as a Procedure on Pro-Bot. Remember to use Repeat Loops when you are working with regular polygons (polygons with all edges equal and all angles equal).
2. Next, construct a net for this triangular prism. Write a program for Pro-Bot to draw the net, using the Procedures for the rectangle and the triangle that you previously wrote.
3. How many different nets can you draw for this triangular prism? Write a program for Pro-Bot to draw each net that you can identify for this prism.

Nets of Pyramids:

The word “pyramid” immediately brings to mind the royal tombs of ancient Egypt. The pyramids of Egypt are square pyramids, with a square base and triangular sides. There are various types of pyramids; they are named according to the shape of the base. A pyramid is made by connecting the base to the apex (top point where all the triangular sides meet). 

In this assignment we shall look at three regular pyramids, which have regular polygons as their base: 

• Triangular Pyramid
• Square Pyramid
• Pentagonal Pyramid

Net of a Triangular Pyramid/Tetrahedron:

A triangular pyramid is also known as a tetrahedron ("having 4 faces"). A tetrahedron has 4 triangular faces, 4 vertices and 6 edges. Three triangular faces meet at each vertex. 

In the figure below, a tetrahedron with 6 cm edges is given. All the triangular faces are equilateral triangles, with sides of 6 cm. 

1. Can you write a program for Pro-Bot to draw a net for the tetrahedron, using the Procedure for the equilateral triangle of sides 6 cm that you wrote earlier? 
2. How many nets can you create for the tetrahedron?
3. After drawing the net using Pro-Bot, you can cut the net out of the paper and fold it along the edges to build the 3D tetrahedron. 

Net of a Square Pyramid:

A square pyramid has 5 faces, 5 vertices and 8 edges. The base is a square and the other faces are triangles. In the figure below, a square pyramid with all edges measuring 6 cm is given. 

1. Can you write a program for Pro-Bot to draw a net for this pyramid, using some of the Procedures that you wrote earlier? 
2. How many nets can you create for the square pyramid?
3. After drawing the net using Pro-Bot, you can cut the net out of the paper and fold it along the edges to build the pyramid. 

Net of a Pentagonal Pyramid:

A pentagonal pyramid has 6 faces, 6 vertices and 10 edges. The base is a pentagon and the other faces are triangles. In the figure below, a pentagonal pyramid with all edges measuring 6 cm is given. 

1. Can you write a program for Pro-Bot to draw a net for this pyramid, using some of the Procedures that you wrote earlier? Remember to use Repeat Loops while writing the program for the pentagon. 
2. How many nets can you create for this pyramid?
3. After drawing the net using Pro-Bot, you can cut the net out of the paper and fold it along the edges to build the pyramid.