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 :)
