US Common core state standards and OER that travels well

I've followed the US Common core state standards (CCSS) initiative (http://www.corestandards.org) with some interest. It's not so much from the point of view of harmonising eduction or setting the same standards across the nation, but I'm more interested in it from the Open Educational Resources (OER) point of view.

One of the main problems for educators who want to use OER as part of their lessons is to find good resources that match their curriculum needs at the moment. Interestingly, the US has the same problem here as we have in Europe: each state/country has their own standards, curriculum topics and descriptions. Additionally, in each state/country topics are taught at different times, in somewhat varying order, etc. (and I'm not touching the issue of different styles of instruction/pedagogy here). This makes it almost impossible to find resources related to a certain curriculum topic from the different state/country. Why? Because the metadata descriptions on which many of the search mechanisms rely upon (at least in repositories and referatories) and their meaning differ from state/country to another. In other words, there is little semantic interoperability.

Let's take an example of mathematics and a targeted competency that is described in the national curriculum. It could be formulated as "Pupils know the symbol rules for whole and rational numbers". In Spain, this is only taught at the first year secondary school when students are 13 years old. But in Finland, this is taught in primary school when students are 12 years old. (NOTE, this is only an illustrative example, I'm totally making the specs up). So the Spanish learning resource which teaches "symbol rules for whole and rational numbers" is described in metadata using "secondary education" and 13-14 years, whereas the Finnish one is described in metadata using "primary education" and 11-12 years. So when the Spanish teacher uses her search criteria relevant to her national curriculum, she will totally miss the Finnish piece OER on the same topic because of lack of semantic interoperability.

From the metadata and search point of view, the CCSS initiative has  put the finger on things (i.e. curriculum topics) that are common across the states and also helps increase semantic interoperability across the stats. I came across an example of this at OER Commons. They use CCSS in their metadata to tag resources that originate from different states but that comply to certain given CCSS topics. See the example here: http://www.oercommons.org/browse/collection/common-core-reference-collection.

Another interesting commonality that I see with CCSS and OER in Europe is related to my previous work on finding OER that "travel well" (see for example here). Basically, in Europe, not all the OER are interesting for sharing across the borders, but only the ones that are useful to others (e.g. curriculum match). But how do we sort out the useful ones from the less useful ones? The CCSS work has figured that out in an interesting way. 

Now, what could we do in Europe? If you have ideas on that, I'll be interested in hearing :)