Replaced images added movies (#472)

* Replaced images image

Replaced CPU image with hand-drawn image. Deleted static images and
added animated GIF movies.

* Added new fidget cube image.

docs/courses/csintro/algorithms/activity.md

@@ -46,7 +46,7 @@ Notes:
 
 * Deleting blocks - Click on the 'forever' block and drag it left to the Toolbox area. You should see a garbage can icon appear. Let go of the block and it should disappear. You can drag any block back to the Toolbox area to delete it from the coding workspace.  You can also remove a block from your coding window by selecting the block and then pressing the "delete" key on your keyboard (or command-X on a mac).
 
->![Trash](/static/courses/csintro/algorithms/trash.png)
+>![Trash](/static/courses/csintro/algorithms/drag-to-trash.gif)
 
 Looking at our pseudocode, we want to make sure to start a program with a clear screen.
 
@@ -148,7 +148,7 @@ Remember, MakeCode automatically compiles and runs your program, so all you need
 * Feel free to play around with turning LEDs on or off in the ‘show leds’ blocks until you get the images you want. 
 * Remember to save your code. 
 
->![Face on micro:bit screen](/static/courses/csintro/algorithms/microbit-screen-face.png)
+>![Face on micro:bit screen](/static/courses/csintro/algorithms/happy-sad.gif)
 
 ## Commenting your code
 It is good practice to add comments to your code. Comments can be useful in a number of ways. Comments can help you remember what a certain block of code does and/or why you chose to program something the way you did. Comments also help others reading your code to understand these same things.

docs/courses/csintro/algorithms/overview.md

@@ -1,4 +1,4 @@
-# Introduction
+`# Introduction
 
 What is a micro:bit?
 The micro:bit was created in 2015 in the UK by the BBC to teach computer science to students. The BBC gave away a micro:bit to every Year 7 student in the UK. You can think of a micro:bit as a mini computer.
@@ -9,7 +9,7 @@ http://microbit.org
 ## What is a computer?
 There are 4 main components that make up any computer:
 
-![Computer components](/static/courses/csintro/algorithms/computer-components.png)
+![Computer components](/static/courses/csintro/algorithms/cpu.png)
 
 1. The Processor – this is usually a small chip inside the computer, and it’s how the computer processes and transforms information. Has anyone heard of the term “CPU”?  CPU stands for Central Processing Unit. You can think of the processor as the Brains of the computer - the faster the processor, the more quickly the computer can think.
 

docs/courses/csintro/algorithms/project.md

@@ -1,5 +1,6 @@
 # Project: Fidget Cube
 
+![Sample fidget cube](/static/courses/csintro/algorithms/fidgetcube.jpg)
 A fidget cube is a little cube with something different that you can manipulate on each surface. There are buttons, switches, and dials, and people who like to “fidget” find it relaxing to push, pull, press, and play with it. In this project, students are challenged to turn the micro:bit into their very own “fidget cube”. 
 
 Show students some examples of fidget cubes: