Easy peasy beans.
I've grown a few bean-plants on my balcony (more than a few actually) and have looked for the best way to get them to germinate. In the beginning I tried sticking them in the ground and just keeping the ground wet, and though that did work for some beans, it also failed plenty of times.
Lots of times my beans got eaten by the larvae of the bean-fly (oh how I hate them!). I went looking for a better way and found something that works very well. This will probably work for other seeds too, and will give you a good idea about the germination rate of your seeds (if you have old seeds you sometimes want to check). I've had no problem transplanting the resulting sprouts, just keep in mind you will have to transplant them at some point. Not all sprouts like that.
Kids will usually love this too. Use beans though, they sprout fast :)
You will need: - a ziploc bag (or another type of firm plastic bag) - some toiletpaper or paper towels - something to spray water with - beans! Take the toiletpaper and put down several layers. Place a few beans on the paper. Spray thoroughly with water until the paper becomes moist with water, but does not drip.
Fold the paper, with the beans in the fold. It helps to not line up the edges so you can check later on. Keep the bag open (very important) and place it in a dark warm place. Most people prefer the top of their fridge, I used a kitchen-cabinet with pipes behind it.
After the first day you may or may not see little roots coming from the bean. Check daily if you prefer, or every other day, to make sure the paper stays moist and to check for beans that rot (it sometimes happens, especially with older beans, they smell bad so it's best to remove the asap).
A few days later, however, the beans have sprouted!
Take it out of the bag, carefully. Make sure not to break any roots.
You'll see here that not all beans sprouted. Two of them rotted (I felt very sad), but the others shot up! The ones on the right I deemed plant-worthy and planted them outside. I took the risk with the two on the left as well, but left the other two (barely rooting) in the bag for a while. If the roots have gone through the paper, don't worry! Just rip the paper and plant it with the bean-sprout. It'll dissolve quickly enough.
Some beans take longer than others, perfectly normal. However, if after a week to ten days you see no action at all, and the beans have gone mushy, they failed. They'll smell bad too.