A Really Quick Introduction to Programming

Posted January 5, 2018

by Lensyl Urbano

With examples using python.

  • Statement: A command given to the computer.
    • Assign a value of -9.8 to a variable called “g”:
    • g = -9.8
    • Print the value of “g” to the screen:
    • print g 
  • Variable: A placeholder name used to record data for later use. In the first statement above, g, is a variable and it is assigned a value of -9.8. Variable names in python start with a letter or underscore “_”. Variables can hold different types of data, for example:
    • strings:
    • x = "hello"
    • Floating point number (aka. a float):
    • x = 9.8
    • Integer:
    • x = 5
    • True/False (aka boolean):
    • x = True 
  • Operations: Statements where some sort of calculation is made:
    • Add two numbers and assign the result to a variable called “y”:
    • y = 3 + 5
    • Divide the value in the variable “y” by 2 and then assign the value to another variable called “z”:
    • z = y / 2
  • Operators: The symbols that tell what operation to do:
    • + – * / are used for addition, subtraction, multiplication, and division respectively
    • ** is used for exponents so 5 squared (52) is:
    • a = 5**2
  • Loops: Tell the computer to do something over and over again. There are different types:
    • “For” loops are good for doing things a set number of times
    • for i in range(5):
      	print i

      results in:

  • Logical statements: These test to see if something is True or False and then do different things based on the outcome:
    • Assign a value to a variable called “x”, check to see if the value is greater than 10, and print out a different sentence based on the result:
    • x = 12
      if (x > 10):
      	print "x is greater than 10"
      	print "x is less than 10"
  • Functions: Chunks of code that someone (maybe even you) wrote that can be referenced via a shortcut:
    • Create a function to calculate the force of gravity at the Earth’s surface if you give it a mass:

      def forceOfGravity(mass):
      	Fg = mass * -9.8
      	return Fg

      Call the function to find the force of gravity acting on a mass of 100 kg and print out the result:

      x = forceOfGravity(100)
      print x

      the result should be:

  • Classes: A class is like a function that you can assign to a variable and then have it do a lot more stuff.
    • In vpython there is a class called “sphere”. It renders a 3d sphere on the screen. Here we’ll create a sphere, assign it to a variable “ball” and then change one of its built-in properties, the color, from the default (white) to red. (if you are using Glowscript.org then don’t use the first line that imports the visual module).

      from visual import *
      ball = sphere()
      ball.color = color.red

Citing this post: Urbano, L., 2018. A Really Quick Introduction to Programming, Retrieved January 23rd, 2018, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

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