Note: The Comments might spoil the answer, be careful.
Number game: use + – * / and parenthesis to make four numbers of 1..9 to a sum of 21. For example : 1 1 3 7 can be used so : 1-1+(3*7)
1) Use numbers : 3 3 8 8
2) Use number : 1 5 6 7
Testing Game, simple :
There is a closed room with three lamps inside. Outside there is are three switches. Each switch operates one lamp. Now, you have to figure out which switch operates which lamp, but you can only use two switches and look at the lamps after you had made all your switching. What do you do ?
Circle and a dot:
Draw a circle and a dot inside it without lifting the pen off paper.