Here are some ideas; I hope they help!

1. Would pattern blocks like these fit the bill, or are they too similar to be useful?

http://www.amazon.com/Pattern-Blocks-Grades-Pre-K-Up/dp/B001HA3FQ8

http://www.mastermindtoys.com/MightyMind-SuperMind-Regular-Edition.aspx

2. Another idea might be standard dominoes.

3. This might be a bit advanced, but it's a beautiful toy with growth potential.

http://www.etsy.com/listing/1141105...gallery_1&ga_search_type=all&ga_includes[0]=tags_exact&ga_search_query=manipulable&ga_facet=manipulable&ga_includes[]=tags_exact&ga_view_type=gallery

4. Something simple that teaches mass, volume, etc. might be interesting, like this basic scale

http://www.learningresources.com/product/primary+bucket+balance.do?sortby=ourPicks&sortby=&

What is to give light must endure burning.