nicole, i see what you are saying.

i think the problem lies in her method of getting what she wants.

if i was in your shoes, if she is screaming for something she wants, there is NO WAY i would give it to her. out of principle. i would nicely explain that while i may have given it to her if she had asked nicely, because she was yelling at me, she wasn't going to get it.

that is the consistency part. she isn't understanding that somethings she can play with and somethings she can't. so she yells for everything. sometimes she gets what she wants and sometimes she doesn't.

i would try to put a stop to her yelling by not giving her whatever she is screaming for... i would wait until she was calm and then offer it to her (maybe 30-60 minutes later, after she's calmed down).

i still occasionally have the same issue with my kids. eg) today, they were absolute nightmares in ikea. because of this, they didn't get any "play time" with mummy and daddy when we got home. it was shower/brush teeth and straight to bed. while normally, they would have had 30 minutes or so after getting home, today they didn't. they need to learn the consequences of their behaviour. and the earlier you start, the easier it should be.

good luck!

PS> as for tempers.... if you were in megabox ikea tonight and heard a crazy white lady yelling at her kids... it wasn't me.....;)