Toshibas and Dell have been the most robust.
You must be joking.......
Besides working as ICT Technician in a Primary School, I also install Espresso, KnowledgeBox and a few other products in schools across the country. The number of times I open a lap trolley and find a pile of Toshiba laptops with keys missing, cracked screens, and other damage! In the school I work at we have always had Toshiba laptops (even the head's has a key missing!) but have just invested in a batch of Lenovo laptops - they have not been subjected to children yet but certainly seem more robust. Also my personal laptop is Lenovo and I am very pleased wit the build quality.
On the subject of wireless - how can any school survive without it??? We have 10 access points spread across 13 classrooms, a meeting room and ICT Suite and never have any significant connectivity problems. The biggest issue we have is the wireless switch being turned off on a laptop.