I agree with 4KookieKids--we also have had our Spielgaben set for three years. It's not cheap, but it's far better quality, and gets a ton more use than similar sets of manipulatives we've used (other geometric 3D solids, block sets, attribute blocks, etc.). It's probably also cheaper, when you consider the random things you pick up. A major benefit to Spielgaben is that it's all made to work together, so you're not limited by different scales, etc. We've gotten rid of pretty much all other manipulatives, except the few other things we use with RightStart Math (I substituted Spielgaben in for many of the materials from the RightStart set, and saved money that way). But the thing is, Spielgaben isn't a set of manipulatives. It's a toy that just has so many uses. My kids (now 6-9 years old) also use various parts at least weekly and often daily. We use it for math in addition to their pulling out various parts and playing and making different things. I know that we will continue to use this set for years. It is perfect for modeling molecules, DNA, etc. There's also not a reason to be wary or suspicious about the "worksheets." I wouldn't refer to them as worksheets at all. Some are similar to patterns you can get for pattern blocks, to copy designs. Others are for ideas of learning some of the many ways one might use the set--for instance, I never would have thought to use tape to stick the blocks together, but this is a great way to do various things and doesn't hurt it at all. My kids were obsessed with making "cameras" out of the blocks for awhile, which is a design presented in on of the books. The math guide is excellent, but I haven't used it as much as I would like. It gives various ideas for activities presenting and practicing different math concepts. The Kindergarten guide is more like a workbook, but even that isn't really. It's more like a cross between pattern block patterns and a Critical Thinking Company book on thinking skills. So, I'd skip the other workbooks you'd buy for preschool-first graders, along with any manipulatives and toys, and just invest in this. It's absolutely worth it in my opinion. Between this and read-aloud books, you've basically got a full preschool-first grade curriculum, and it will continue being fun for both school and play for many years after.

We have also had our Spielgaben set for three years. My kids are now 6-9 years old, and still use it at least weekly, and often daily. I ended up buying it to not have so many different types of similar things, but of cheaper quality. I LOVE Spielgaben in that it all works together. We use is regularly with our math, substituting Spielgaben for other manipulatives (sticks for tally sticks, square tiles, geometric 3D shapes, etc.). The kids use it for free play also. We will be living all in one room for a few months while having major house work done, and Spielgaben is the one "toy" that we will be bringing with us, because I know that the kids use it in so many ways for so many different things. They're pretty good about putting it away. When we first got it, there were a couple of times when they decided to make "soup" by mixing everything together, and that wasn't so fun to deal with, but that was thankfully rare and short-lived. They like the sticks and balls very best and make a lot of spinning tops these days, among other things. But they use all parts of this set at different times. My only regret is that I didn't buy it sooner, when my oldest was younger (more like 3 or 4 instead of 6). I would have used this in place of so many other things we had. If you have the means, I definitely recommend it. This and cheaper versions of magnatiles have been my kids' favorite toys. I don't think we really needed anything else. This also would be a perfectly fine preschool-1st grade curriculum, with some read-alouds thrown in. It works for math, letter learning (make them out of sticks and curves, like Handwriting Without Tears). Like I said, if I did it over, I would have gotten it sooner and not purchased other educational materials other than books for that age. I foresee us using it for years still to come, and it will be one of the few things I will keep around for small visitors and grandchildren when my kids grow out of it (if they ever do...). We have used it to create molecule models, and I already have visions of creating DNA models out of this as well!