I have 4 little ones all under 3 and I do monthly themes with them and they all enjoy it. As long as it's done properly, it can be very beneficial and enjoyable for everyone. Children are all about patterning and I try to incorporate themes that allow them to make connections to things around them. For instance, Sept and Oct we are looking at Fall and we'll be examining apples, pumpkins, leaves, color changes. Children learn best through play, so by incorporating these themes throughout your playroom centers you can support child initiated play. For example, book center (books about fall, leaves etc...), science (nature walk, collecting leaves), sensory bin (apples, leaves, pinecones, mini pumpkins), math (counting pumpkins, apples, leaves, acorns), dress up (straw hats, shirts, jeans and we have a scarecrow in the area and when the kids are pointing their clothes on, they look like the scarecrow).

Also even though I do a theme on something, once it's done it's not like the children will never see some of these things again for another year. As playfelt mentioned above, if children are interested in dinosaurs once the theme is done, then they can still play with the dinosaurs during our fall time...the dinosaurs can hide amongst the leaves etc,

I think themes are a great way to engage children at any age. But, I also sing lots of songs, read lots of books, do lots of felt stories that are not related to the theme.

It's also important to allow children be a part of creating the theme...today for instance we're hanging up leaves for our fall theme, and all my little ones took turns helping and they loved it, clapping their hands when a new one was added.

I also just finished a "under the sea" theme for summer and they got such a kick out of it. We talked about water, animals in the sea and my children especially loved it when we focused on fishes. Other fun ones are: all about me, transportation (i have a little boy who is obsessed with this one, so needless to say every day is transportation theme for him), insects & butterflies...all of these are things they can see everyday, which makes it very real for them.

Good luck!