If you are reffering to what to do when your Tamagotchi is in school:
In Preschool:
Just keep sending it to school over and over again everyday until you stop recieving any skill points for that day. Skill points distributed in preschool are random. And you have to make sure you press B when the AWAY sign is up to go to school or no progress is made.
In Regular School:
After choosing your teacher to determine the type of points you wish to recieve, just watch the presents. Your points always start in the left box. Every time the boxes blink, the contents in those boxes switch. You just have to watch the box with your points in it and select the correct one when you get the chance to pick. The boxes only switch a total of 4 times, even though your points aren't always included in those switches.
Hope this helps