Generating menus with classes

[Heyjoe]

Hello fellow Python Users,

You need to make an object to use a class. I did make an object in the third line from the last "m=Main(root)# ". However, I don't understand why I was able to generate menus from the following classes, since I did not make an object for them. The classes are FirstMenu, SecondMenu, ThirdMenu.

Wouldn't I need something like:
f = FirstMenu(root)
s = SecondMenu(root)
t = ThirdMenu(root)

My code works but I would like to understand it better. Why was I able to get the menus to work without making an object for each class?

import tkinter as tk
root = tk.Tk()

myfont = "helvitica 25"
mybg = "light sky blue"
myheight = 4
mywidth = 60
myheight2 = 2
mywidth2 = 20
myheight3 = 2
mywidth3 = 20
labcol = "spring green"
anscol = "yellow"
otherbutcol = "skyblue"
commandbutcol = "light sky blue"
mypadx = 0
mypady = 0

class Main:


    def __init__(self, root):
        self.root = root
        root.geometry('1200x1200')
        self.theframe = tk.Frame(root)
        self.theframe.pack()
        FirstMenu(root)

    def desframe(self):
        self.theframe.destroy()

    def iw(self):
        pass

class FirstMenu:

    def __init__(self, root):
        self.root = root
        root.geometry('1200x1200')

        self.theframe = tk.Frame(root)
        self.theframe.pack()
        self.fstmenu()

    def fstmenu(self):
        self.fstlabel = tk.Label(self.theframe, text="First Label", bg=["springgreen"], font=myfont,
                                       relief="groove")
        self.fstlabel.config(height=myheight, width=mywidth)
        self.fstlabel.pack()
        self.fstbutton = tk.Button(self.theframe, text="Click here to start.", bg=["springgreen"], font=myfont,
                                     relief="groove", command=lambda: [self.desframe(),SecondMenu(root)])
        self.fstbutton.config(height=myheight, width=mywidth)
        self.fstbutton.pack()

    def desframe(self):
        self.theframe.destroy()

class SecondMenu:


    def __init__(self, root):
        self.root = root
        root.geometry('1200x1200')

        self.theframe = tk.Frame(root)
        self.theframe.pack()
        self.secmenu()

    def secmenu(self):
        self.seclabel = tk.Label(self.theframe, text="Second Label", bg="red", font=myfont,
                                       relief="groove")
        self.seclabel.config(height=myheight, width=mywidth)
        self.seclabel.pack()
        self.secbutton = tk.Button(self.theframe, text = "This is your second click.", bg="red", font=myfont,
                                     relief="groove", command=lambda: [self.desframe(),ThirdMenu(root)])
        self.secbutton.config(height=myheight, width=mywidth)
        self.secbutton.pack()

    def desframe(self):
        self.theframe.destroy()


class ThirdMenu:


    def __init__(self, root):
        self.root = root
        root.geometry('1200x1200')

        self.theframe = tk.Frame(root)
        self.theframe.pack()
        self.thirdmenu()

    def thirdmenu(self):
        self.thirdlabel = tk.Label(self.theframe, text="Third Label", bg="purple", font=myfont,
                                       relief="groove")
        self.thirdlabel.config(height=myheight, width=mywidth)
        self.thirdlabel.pack()
        self.thirdbutton = tk.Button(self.theframe, text = "This is your third click.", bg="purple",font = myfont, command=lambda: [self.desframe(),ThirdMenu(root)])
        self.thirdbutton.config(height=myheight, width=mywidth)
        self.thirdbutton.pack()

    def desframe(self):
        self.theframe.destroy()
m=Main(root)# **smile** 
root.mainloop()