book = [ "Archaeology", "Art", "Biology", "Chemistry",
         "Computing", "English", "French", "Geography",
         "History", "Maths", "Psychology"]

found = False        # This is a flag - is it found or not?
left = 0             # Set left to 0 (first item in the list - Archaeology)
right = len(book) - 1  # Set right to the length of the list minus one (last item in the list)
find = "Maths"

#Repeat the following until item found, or you have check every item in the list
while found == False and left<=right:   
    mid = (left + right) // 2   # Calculates the midpoint
    if book[mid] == find:       # Check does the item we're looking at == search item
        found = True            # If it is, set found to True - we've found our search item!
        index = mid
    else:
        # If not found, move the left or right pointer to the midpoint
        # Depending on what side of the list we want to search next
        if find > book[mid]:
            left = mid + 1
        else:
            right = mid - 1
    # Return to the while loop and re-check the conditions
    # Continue repeating until item found or all items checked

# Output if the item is found or not
if found:
    print("Item successfully found at position", index)
else:
    print("Search term not found.")