DataGridView和List绑定不显示问题

在学习DataGridView 和List<T>绑定时发现DataGridView不会显示数据。后来发现要用类的属性才能正常显示，如果直接用类的字段等来显示，则无法显示数据。

代码如下：

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;



namespace WindowsFormsApplication20

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }



        private void Form1_Load(object sender, EventArgs e)

        {

           

            dgv_message.GridColor = Color.Blue;           

            dgv_message.DataSource = new List<student>()

            {

                new student(){sName="小李",Age=20},

                new student(){sName="小张",Age=40},

                new student(){sName="小王",Age=60},

                new student(){sName="小黄",Age=22}

            };

                           

               dgv_message.Columns[0].HeaderText = "姓名";

               dgv_message.Columns[1].HeaderText = "年龄";

            

        }

    }

    public class student

    {

       private string name;

       private  int age;



        public string sName

       {

           get { return name; }

           set { name = value; }

       }



        public int Age

        {

            get { return age; }

            set { age =value ; }

        }

    }

}

如果把student中类变成以下代码，则无法显示：

    public class student

    {

       public string sName;

       public int Age;      

    }