Offset function on selective columns in Excel VBA - vba

Question

Bit new to VBA. It seems quite simple though; am not able to figure it out how to use Offset function and While/Do while loop here.
I am making an excel form where columns A to L will have values.
Out of which few columns are mandatory. Those are A, B, C, D, F, G, H, I, J, L.
Which means those can't be left blank and other columns can be blank.
My excel looks like below.
I have written a code where it checks whether mandatory columns have values or not.
The code is as below :
Dim celadr, celval As Variant
Dim cell As Variant
Dim LastRow As Long
LastRow = Range("A65536").End(xlUp).Row
On Error GoTo 0
shname = ActiveSheet.Name
Dim celArray, arr, Key1, KeyCell As Variant
celArray = ("A,B,C,D,F,G,H,I,J,L")
arr = Split(celArray, ",")
For Key1 = LBound(arr) To UBound(arr)
KeyCell = arr(Key1)
Range(KeyCell & "2:" & KeyCell & "" & LastRow).Select
'Selection.Clearformats
For Each cell In Selection
celadr = cell.Address
celval = cell.Value
If celval = "" Then
Range(celadr).Interior.Color = vbRed
strErr = Range(celadr).Value
Sheets("Observations").Range("A65536").End(xlUp).Offset(1, 0).Value = IIf(strErr = "", "Empty Found", strErr)
strstr = "'" & shname & "'!" & Range(celadr).Address(0, 0)
Sheets("Observations").Hyperlinks.Add Anchor:=Sheets("Observations").Range("A65536").End(xlUp), Address:="", SubAddress:= _
strstr, TextToDisplay:=IIf(strErr = "", "Empty Found", strErr)
End If
Next cell
Next Key1
The result of this code is;
1) between each two school records a row may be left blank.
My above code will color such all rows also in red background.
(It should not happen)
2) Columns B, C, D, F, G, H can have values only in the same row in which school_name is mentioned.
So, if following rows for same school are left blank then those also will be colored in red background.
(It should not happen).
So; I want to make small correction to code:
I want to add a condition to code:
"When there is a value in Column A; then only the above code should be exceuted."
I tried to achieve it as I have written in below Code. Still, am not upto.
I have commented all such lines of code which were giving me error (from below code):
Dim celadr, celval, celadr1, celval1 As Variant
Dim cell, cell1 As Variant
Dim LastRow As Long
LastRow = Range("A65536").End(xlUp).Row
On Error GoTo 0
shname = ActiveSheet.Name
Dim celArray, arr, Key1, KeyCell As Variant
'Range("A2:A" & LastRow).Select
'For Each cell1 In Selection
'celadr1 = cell1.Address
'celval1 = cell1.Value
'Do While Len(celval1) >= 1
celArray = ("A,B,C,D,F,G,H,I,J,L")
arr = Split(celArray, ",")
For Key1 = LBound(arr) To UBound(arr)
KeyCell = arr(Key1)
Range(KeyCell & "2:" & KeyCell & "" & LastRow).Select
'Selection.Clearformats
For Each cell In Selection
celadr = cell.Address
celval = cell.Value
' May be another loop over here to increment value in offset function according to column number.
If celval = "" Then 'And Offset Function Referring to column A, same row.
Range(celadr).Interior.Color = vbRed
strErr = Range(celadr).Value
Sheets("Observations").Range("A65536").End(xlUp).Offset(1, 0).Value = IIf(strErr = "", "Empty Found", strErr)
strstr = "'" & shname & "'!" & Range(celadr).Address(0, 0)
Sheets("Observations").Hyperlinks.Add Anchor:=Sheets("Observations").Range("A65536").End(xlUp), Address:="", SubAddress:= _
strstr, TextToDisplay:=IIf(strErr = "", "Empty Found", strErr)
End If
' End If
Next cell
Next Key1
' Loop
Can someone guide me how I can make correct use of offset function/while loops here?
Edit:
Assume, XYZ School don't have value for No. of Teachers
And
PQRS School don't have value for No. of students
My Current output is as in below image:
Where as Expected Output is:

Answer 1

I think the below code should work - try it out and let me know if there are any issues:
Sub Your_Macro()
Dim celArray, item As Variant
Dim LastRow, x As Long
LastRow = Cells(rows.Count, "A").End(xlUp).row
celArray = ("A,B,C,D,F,G,H,I,J,L")
celArray = Split(celArray, ",")
For x = 2 To LastRow
If Not IsEmpty(Cells(x, "A")) Then
For Each item In celArray
If IsEmpty(Cells(x, item)) Then
Cells(x, item).Interior.Color = vbRed
End If
Next item
End If
Next x
End Sub