If statements

Here is the code from the evening class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace IfExamples
{
    class IfStatements
    {
        static void Main(string[] args)
        {
            IfStatements ifs = new IfStatements();
            //ifs.SimpleIfStatement();
            //ifs.IfElseExample();
            ifs.SwitchExample();
            ifs.PauseIt();
        }//end main

        private void SimpleIfStatement()
        {
            Console.WriteLine("Enter an age");
            int age = int.Parse(Console.ReadLine());
           //equality ==
            //!= not equal

            if (age > 75)
            {
                Console.WriteLine("You are old");
            }
            else
            {
                Console.WriteLine("You are a spring chicken");
            }
        }//end SimpleIf

        private void PauseIt()
        {
            Console.WriteLine("Press any key to exit");
            Console.ReadKey();


        }//end PauseIt

        private void IfElseExample()
        {
            bool isInteger;
            int score;
            Console.WriteLine("Enter your test Score");
             isInteger= int.TryParse(Console.ReadLine(), out score);

             if (isInteger == false)
             {
                 Console.WriteLine("Next time enter a number");
                 return;
             }

            int grade = 0;

            if (score >= 90)
            {
                grade = 4;
            }
            else if (score >= 80)
            {
                grade = 3;
            }
            else if (score >= 70)
            {
                grade = 2;
            }
            else if (score >= 60)
            {
                grade = 1;
            }
            else
            {
                grade = 0;
            }

            Console.WriteLine("Your Grade is {0}", grade);
        }//end ifelse

        private void SwitchExample()
        {
            int choice;
            Console.WriteLine("Choose which method to run");
            Console.WriteLine("1: SimpleIfStatement");
            Console.WriteLine("2: IfElseExample");
            Console.WriteLine("3: Exit");

            choice = int.Parse(Console.ReadLine());

            switch (choice)
            {
                case 1:
                    SimpleIfStatement();
                    break;
                case 2:
                    IfElseExample();
                    break;
                case 3:
                    PauseIt();
                    break;
                default:
                    Console.WriteLine("Not a valid choice");
                    break;
            }

        }//end switch

        //if (number > 0 && number < 100) and
        //if (number < 0 || number > 100) or

    }//end class
}