Dim userName As String
Dim visitedPart1 As Boolean 'ADDED
Dim visitedPart2 As Boolean 'ADDED
Dim visitedPart3 As Boolean 'ADDED

Sub GetStarted()
    Initialize
    YourName
    ActivePresentation.SlideShowWindow.View.Next
End Sub

Sub Initialize()
    HideQuizButton 'ADDED
    visitedPart1 = False 'ADDED
    visitedPart2 = False 'ADDED
    visitedPart3 = False 'ADDED
    ActivePresentation.Slides(2).Shapes(6).Visible = False
    ActivePresentation.Slides(2).Shapes(7).Visible = False
    ActivePresentation.Slides(2).Shapes(8).Visible = False
End Sub

Sub YourName()
    userName = InputBox(prompt:="Type your name")
End Sub

Sub HideQuizButton() 'ADDED
    ActivePresentation.Slides(2).Shapes(5).Visible = False
End Sub

Sub ShowQuizButton() 'ADDED
    ActivePresentation.Slides(2).Shapes(5).Visible = True
End Sub

Sub DoWeShowQuizButton() 'ADDED
    If visitedPart1 = True And visitedPart2 = True _
        And visitedPart3 = True Then
        ShowQuizButton
    Else
        HideQuizButton
    End If
End Sub

Sub ReturnToMenuFromPart1()
    visitedPart1 = True 'ADDED
    ActivePresentation.Slides(2).Shapes(6).Visible = True
    JumpToMenu
End Sub

Sub ReturnToMenuFromPart2()
    visitedPart2 = True 'ADDED
    ActivePresentation.Slides(2).Shapes(7).Visible = True
    JumpToMenu
End Sub

Sub ReturnToMenuFromPart3()
    visitedPart3 = True 'ADDED
    ActivePresentation.Slides(2).Shapes(8).Visible = True
    JumpToMenu
End Sub

Sub JumpToMenu()
    DoWeShowQuizButton 'ADDED
    ActivePresentation.SlideShowWindow.View.GotoSlide (2)
End Sub

Sub RightAnswer()
    DoingWell
    ActivePresentation.SlideShowWindow.View.Next
End Sub

Sub DoingWell()
    MsgBox ("You are doing well, " & userName)
End Sub

Sub WrongAnswer()
    DoingPoorly
    ActivePresentation.SlideShowWindow.View.Next
End Sub

Sub DoingPoorly()
    MsgBox ("Try to do better next time, " & userName)
End Sub