"I read this article, changed my method, and was amazed when a week later my 18 mo. old knew his colors backward and forward." Even if you're not trying to teach colors, read this article from Scientific American, it's fascinating!
Indoor gross motor game that teaches or reinforces colors. It could also be modified to teach other concepts like shapes, letters or numbers. A simple and great way to stay active even when stuck indoors!
Color and Movement for a Rainy Day ~ Learn Play Imagine