Lesson Plan
The lesson plan for our lesson on variables
To define a variable in python, just type in the variable name - one word - and use the = sign to set it equal to it's value. A variable can be defined using numbers, string, list, or boolean. Strings must have quotations around it and lists must be surrounded by square brackets. Once you have defined a variable, you can do many functions and conditions with it, including the print() statement.
#defining all the variables using the equal sign
numbervariable = 25
stringvariable = "word"
numberlist = [1, 2, 3, 4, 5]
stringlist = ["a", "b", "c", "d", "e"]
israining = False
#printing all the defined variables
print(numbervariable)
print(stringvariable)
print(numberlist)
print(stringlist)
print(israining)
Once a variable is defined using a numerical value, mathematical expressions can also be performed on the variable.
number = 5 #defining the variable number
x = number * 2 #defining a variable by using another variable
print(number*2) # multiplying a variable by 2
print(x)
Once a list is defined, many functions can be performed, such as the append() function.
list = []
list.append("cookies") # appending a value to a defined list
print(list)
A dictionary can also be defined using curly brackets and the equal sign. To input keys and values into a dictionary, you have to use a slightly different approach than lists.
mydict = {"ice cream":"dairy"} # defining dictionary using curly brackets
mydict["banana"] = "fruit" #add keys and values to a dict by setting a value equal to a key, like shown
mydict["ice cream"] = "dessert" #editing a value inside the dictionary
print(mydict)
You can also interchange variables by using a temporary variable. In the code below, temp is the temporary variables, and var 1 and var 2 will have their values swapped. This code also works with integers, not just strings.
var1 = "word" # defining first variable
var2 = "number" # defining second variable
temp = var1 # defining temporary variable using the first variable
var1 = var2 # changing the first variable value as the second variable value
var2 = temp # changing the second variable value to the first variable value
Variables can also be defined using float data types, instead of just int types, but are used the exact same way. The same mathematical functions also apply.
number = 20.3 #defining a variable usinbg float
x = number/10 #defining second variable
y = number*2 # defining third variable
print(number) # printing first variable
print(x) #printing second variable
print(y) # printing third variable
print(x*y) #printing the second and third variables multiplied
The function below takes in a parameter, x, and determines if x is even or odd. Variables can be used within functions to perform a certain task, which in this case, is to determine even or odd. To define a function, use the variable def and use a colon. Make sure there are parenthesis next to the function name, even if the function doesn't tkae in any parameters.
def IsEven(x): # define the function
if x % 2 == 0: # % variable returns the remainder of division
# use double equal signs when determining if a value is equal to another value
return True
if x % 2 != 0: # the != means not equal to
return False
#printing the values outputted by the function multiple times
print(IsEven(24))
print(IsEven(7))
print(IsEven(19))
print(IsEven(30))