why am i getting System.Collections.Generic.List`1[System.String] when i try to print values froma list?

I'm trying to create a session where i store the values of certain column. so I created this list to display the value if selected but I'm getting this in the other page System.Collections.Generic.List`1[System.String] instead oof the actual values.

this is the first page's code:

Private Sub BindGrid()
    Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("dbconnection").ConnectionString)
    con.Open()
    Dim cmd As New SqlCommand("select distinct Name,assignment_id, Description ,cod from assignments 
        INNER Join crmsLecturerXCrsSection ON crmsLecturerXCrsSection.emp_key = assignments.emp_key
        INNER Join CRMSStudentsXCrsSection ON CRMSStudentsXCrsSection.CrsSec_id = crmsLecturerXCrsSection.CrsSec_id
        INNER JOIN CRMS_CourseXSection ON CRMS_CourseXSection.CrsSec_id = CRMSStudentsXCrsSection.CrsSec_id
        INNER JOIN CRMSECTIONS ON CRMSECTIONS.SEC_ID = CRMS_CourseXSection.SEC_ID
        left JOIN crmscourses ON crmscourses.crs_id = CRMS_CourseXSection.crs_id
        INNER JOIN CRMS_CourseXSection cs ON CRMS_CourseXSection.SEC_ID = CRMSECTIONS.SEC_ID
        INNER JOIN CRMSSEMESTER ON CRMSSEMESTER.SEM_ID = CRMS_CourseXSection.SEM_ID
        where  CRMSSEMESTER.SEM_ID='1'   
        and crmsLecturerXCrsSection.emp_key='436' and crmscourses.crs_desc='" + Session("crs") + "'", con)




    Dim da As New SqlDataAdapter(cmd)
    Dim dt As New DataTable()
    da.Fill(dt)

    Dim listIDs As New List(Of String)
    Dim row As DataRow
    For Each row In dt.Rows
        listIDs.Add(row("assignment_id"))
    Next
    Session("assid") = listIDs




    cmd.Connection = con

    GridView1.DataSource = cmd.ExecuteReader()
    GridView1.DataBind()




End Sub

this is the second's:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Label1.Text = Session("assid").ToString()

    Dim con1 As New SqlConnection(ConfigurationManager.ConnectionStrings("dbconnection").ConnectionString)

    Dim cmd1 As New SqlCommand("select * from assignments where assignment_id ='" + String.Join(",", Session("assid")) + "'", con1)
End Sub