growing algae

Hi, is there an easy way to grow green algae in a bowl or something so I can scrape it off and dump it in my main tank for food? Can I just fill a glass container and stick it in the sun? I remember seeing a thread about this before but I didn't consider doing it till now.

Hi everyone, because I will be getting fish in the future that will snack on algae in my tanks, I was thinking of a algae producing tank to make algae covered rocks for them to munch on. So I need to know what would be the absolute fastest way of producing algae in an aquarium. -Thanks