that didnt work, i suggest http://sgknitting.blogspot.com/ and scroll down. that link goes to legos 404 page
Sounds like an interesting and yet achievable plan. But since you seem to have licked blood now, nobody is stopping you from offering extra afternoons at your house in the summer holidays for those kids who catch fire, right? (If you have the time and inclination to continue - but it does sound like fun, and with nice kids…)
Of course we are all eagerly awaiting your tales of daring-doo!
Not a problem. I wish I was young enough to go to your class.
Write on the paper, put the stamp/sticker over it. Stamp/sticker must be steamed off to read. Reader knows it is their because of the orientation of the stamp/sticker(i.e. stamp is upside down there is a message). This can also be used instead of the greeting from my example above. 90 degrees to the right, hidden on envolope, 90 to the left, on the letter.
-Otanx
Don’t they all just say “Drink more Ovaltine”?
Shhhhhhhhhhhhh!!
The project week is almost over, so here is an update as to how it actually worked out.
I wasn’t there on Tuesday, the first day of the project, but the others showed the kids how to write messages with lemon juice. Very fine, and only one minor fillip: in holding the paper over a candle to make the lemon juice visible, one kid caught his message on fire and dropped it on the carpet, where it was stamped out. It does not show my most mature side that I snickered every time I saw the dark smudge, right?
The time just flew by each day, so I ended up cutting out almost half of what I had planned. We didn’t bother to do anything more with invisible inks after that first day (although I brought my iron along yesterday and today for safety’s sake), but I showed all three groups the letter pairs code, which they picked up right away, and we made code wheels, and today I showed them the grid code and gave them new messages in the letter pairs code.
Tomorrow will be the big day: they’ll have a case to solve, with fingerprints, footprints, a coded message, and other clues to detect.
And now I’m off to shower off the grubbiness of the morning – another mother and I were shadowed by the kids as we walked along different streets, exchanged cloth bags, exchanged a newspaper on a bench, and left a coded message at a dead drop (a matchbox hidden under the bench).
The decoded message, by the way, reads: “Careful! The kid next to you might be a spy!” 
And if I haven’t already made it clear, this has been the most funnest week EVER.
Whee! Keep it comin’, shantih!