I have life insurance, Roth IRA, and State Teachers Retirement that I'd like to leave if something happens to me.
Unless your estate is the beneficiary (if you didn't name a bene., then your estate is the bene.), none of those assets are directed by a will.
Wills can only direct probateable assets. If you name the bene's for life insurance, retirement accounts, pensions, trusts (can become complicated, depending on the structure of the trust... long story short, assume it is non-probateable... there can be exceptions depending on it's setup),etc. the assets will move along as directed by law. Remember Probate is public record, and is thus open for all to see (not private whether you like it or not).
Proper estate planning can leave nothing in the probateable portion of the estate... this will save money, due to the fact a judge/probate court doesn't need to get involved (expenses associated with probate are avoided)... also, assets directed by law are very difficult to contest... that's not the case with probateable assets (wills are contested all the time).
I'm not an attorney, and this post isn't intended to be the practice of law... it's an fyi to talk to a good attorney specializing in these matters (another fyi, a good attorney can "freeze" a lot of assets in a variety of ways, saving estate taxes... I'm not going to list the many, many ways this can be done... many folks don't care if their stuff is "public knowledge" nor do they have enough assets to care about "shrinking the estate"... with that said, most folks need advice and don't know they need it...)
The short story is to talk to an attorney and have a plan in place... I happen to work with "high net worth" individuals, and this is a subject I run into often. I'm amazed that there are so many folks out there that really don't know they could be passing more assets to chosen destinations (read, anywhere other than the gov.) and keep everything private...
Edit: As an example Bill Gates will not pay a nickel in estate taxes... there isn't a single asset (down to his socks) that is probateable...