these are some instuctions that are very simular to ones i found on a variety of sites. this is how im going to make my own slits.

1) find some healthy sweet potatoes. No openings in the skin, soft spots or mold. Basically if it looks good enough to eat then you are good to go. You can find them at your local farmer's market in the fall or just go pick out some at your local grocery store or use some that you grew the previous year and stored in a cool dark place all winter.

2) Grab one sweet potato, two toothpicks and a jar or a water tight container that the potato can stand upright in without tipping over. The toothpicks will serve as a platform so that the roots have room to develop. Very Carefully push one toothpick all the way through the sweet potato about half way down . Do the same with the other toothpick and therefore making a(+)with the toothpicks if looking down on the sweet potato vertically. Sometimes it helps to twist the toothpick if it gets stuck when you are pushing it through the sweet potato.You will probably break a few toothpicks in the process.

3) Place your newly punctured sweet potato in the jar so that all four toothpick ends rest on the rim of the jar.

4)Fill the jar with water and set it in a sunny window facing East. Check the water level about every day. Make sure the jar stays full. In a few weeks purple eyes will start to emerge from the top and white roots from the bottom. Soon after, the eyes will sprout leaves. Each eye will grow into a slip. When a vine from an eye grows to six inches pinch it off where green meets purple and another slip will grow in its place.