Teaching any religion... or good moral values for that matter... to children can be challenging as we try to explain the "why" behind things so they can then understand where the line is. But what if that line is so grey that we can't precisely describe it until they cross it?
Some things are easy... how to pray, how to fast, how to say Shahadah. Some things aren't so simple... when is water too dirty to do wudu with, how much filth is too much, how do you calculate zakat? Alhamdulilah, we have so many organizations now that can help spread this knowledge to anyone who is willing to learn. The challenge really becomes us parents taking the time on a consistent basis to teach. One of my biggest downfalls is consistency with things such as this.
I say we are going to study Islam over the summer and we agree and she even picks the first topic, learning about prophet Hud. Then one day passes by the next where the time escapes us and we miss our opportunity that was right in front of our face, but we used it for something less important.
InshaAllah we all can take the time to make teaching our kids Islam as important as it really is. If we don't show them how critical this is, we can't expect them to pick that up once a week in Sunday school. Those grey areas become more clear with continued practice and implementation.