Dim username As String
Dim visited() As Boolean
Dim numSlides As Long
Dim numRead As Integer
Dim numWanted As Integer

Sub GetStarted()
    Initialize
    YourName
    RandomNext
End Sub

Sub Initialize()
    Randomize
    numWanted = 5
    numRead = 0
    numSlides = ActivePresentation.Slides.Count
    ReDim visited(numSlides)
    For i = 2 To numSlides - 1
        visited(i) = False
    Next i
End Sub

Sub YourName()
    username = InputBox("What is your name?")
End Sub

Sub RightAnswer()
    DoingWell
    visited(ActivePresentation.SlideShowWindow.View.Slide.SlideIndex) = True
    numRead = numRead + 1
    RandomNext
End Sub

Sub WrongAnswer()
    DoingPoorly
End Sub

Sub DoingWell()
    MsgBox ("Good job, " & username & ".")
End Sub

Sub DoingPoorly()
    MsgBox ("Try again, " & username & ".")
End Sub

Sub RandomNext()
    Dim nextSlide As Long
    
    If numRead >= numWanted Or numRead >= numSlides - 2 Then
        ActivePresentation.SlideShowWindow.View.Last
    Else
        nextSlide = Int((numSlides - 2) * Rnd + 2)
        While visited(nextSlide) = True
            nextSlide = Int((numSlides - 2) * Rnd + 2)
        Wend
        ActivePresentation.SlideShowWindow.View.GotoSlide (nextSlide)
    End If
End Sub