what is a "science level"?

[mindstar]

How do I allow to build or upgrade more structures at the same time? It says it's limited "according to your science level" but I can't find where this level is or how it is defined?

[lienadla]

You need to upgrade your Construction science and you can find it in your science page (the green potion icon beside the treasure chest).

[sliph]

Look on the science page, it's the very top (first) science. The two crossed hammers.