A ghost has three oil lamps. The first lamp uses 1 lbs of oil in 1 night, the second lamp uses twice as much oil as the first lamp, and the third lamp uses 3 lbs of oil in 1 night.
Now, this ghost has a special tradition when it comes to using his oil lamps. He lights up the first two lamps during the first 10 nights and on the 11th night he adds the third lamp.
For how many nights will the lamps burn if there are 90 lbs of oil in the ghost's storage?
Ok. In the beginning the kids were enthusiastic about the story. They drew the lamps and the owner of the lamps. They were able to figure many things on their own and with certain things I had to help them. Then we got to the part, where I wanted them to write down all the steps of the solution and here it started. There are seven steps and my poor kids thought it was some kind of sophisticated torture exercise because I kept on asking, "And how many oil lamps this and that....?". After a certain point the kids started to give me just random answers about those ridiculous oil lamps and it was frustrating and hilarious at the same time.
When it was all over, I turned to my friend, who was there, and I said to her, "It was a complete failure. I totally lost them." My friend, who is the sweetest person on earth, said, "You did great. Really. They are little but they have to learn it anyway. Let me buy you lunch".
Hahaha Those oil lamps. Argh. Never again.