Additionally, (Rice University) offers free Social Sciences textbooks in Spanish, though they are designed for university level, not ESO.
If you are looking for specific content typically found in these PDFs, here is a breakdown of a standard unit: ciencias+sociales+edelvives+pdf
to explore their full catalog of Social Science materials and official digital access options. (e.g., 5º Primaria) or a particular project series (e.g., Sirabún) for your blog? OPL Monitor - Apps on Google Play ciencias+sociales+edelvives+pdf