Many single Mums feel it is important to teach their sons to stand when urinating, when in fact, it is not that important. A toddler usually has a very small penis that points straight out. Standing up to urinate can be difficult if not impossible. Usually, they will end up urinating on the back of the potty or toilet, or all over the floor and wall.
When your son gets older, you will be able to teach him and he should catch on in one day. You can also implore the assistance of a male in the family. Your son might actually be more comfortable learning this from a male instead of his Mum.