KlasCement is an educational online network by and for Dutch-speaking teachers (mostly from Flanders, Belgium). The website is also available in English, the content is mostly in Dutch.
Membership is free. Our members exchange educational resources they've used in their classroom or made themselves: manuals, worksheets, sites, apps, exercises, multimedia,... We share via (and stimulate the use of) Creative Commons licenses. Educational organisations use KlasCement as well, to announce their activities. Every member can upload, rate, comment, save items as personal favourites, …
It's a real bottom-up crowdsourced database of user-generated educational content, combined with professional content via partnerships with organisations and even publishers. All content has to be approved by a team of teachers. They validate learning resources, help teachers with copyright issues and add standardized metadata.
KlasCement started in 1998 (!) as an initiative from one teacher. The portal received financial support from the Flemish Ministry of Education as from 2002 as part of a non-profit organisation and became part of the MoE in 2013.
In 2017, KlasCement has 120 000 unique and active members; almost 50% of all Flemish teachers use the network regularly. Almost 50 000 educational resources have already been shared. On a monthly basis, we have more than 300 000 downloads! More than 10% of the users is sharing content. You don't have to share, but it's highly appreciated if you do so.
Main Website: http://www.klascement.net