image courtesy of The LEGO Group
Customers had complained there weren't LEGO sets attracting enough young girls to build -- so The LEGO Group invested tons of money & time in an anthropological research project spanning the globe comprised of thousands of *real* girls and their families to develop a Gateway theme into construction toy play. In 2011 only 9% of LEGO builders were girls; now that Friends sets are available, that number has increased to 27% (per The LEGO Group).
These sets have the same creative, building toy as all LEGO. Olivia's House set box contains 700 loose bricks and instructions. Girls can then re-build the bricks blending in bricks from any other LEGO set or brick bucket.
Now more girls are gaining STEM skills through spatial-reasoning involved in building and re-building these toys. They also gain technology skills by accessing interfaced programs, such as LEGO Digital Designer to create CAD-type version of these sets -- as well as manipulate the bricks in that virtual platform to create anything she can imagine!