# [Edu-sig] Sample Lesson Plan

**Guido van Rossum
**
guido@python.org

*Fri, 04 Feb 2000 09:13:29 -0500*

Nice lesson!
I got lost with tetra() at first because it lacked a picture :-)
Also, I've never seen
for i in range(n+1)[1:]:
to write a loop from 1 to n; it seems better to write
for i in range(1, n+1):
You could also write
for i in range(n):
sum = sum + tri(i+1)
Finally, is it a pedagogical device to start with recursion and then
write a for loop? I suppose tetra(n) is easily defined recursively:
def tetra(n):
if n <= 1: return n
else: return tetra(n-1) + tri(n)
--Guido van Rossum (home page: http://www.python.org/~guido/)