Microsoft is rolling out a custom version of Bing this week tailored specifically for classrooms. School administrators can enable an ad-free version of Bing with always-on SafeSearch — Microsoft’s web security and adult content filtering — and daily literacy lesson plans. A pilot program kicked off last August and more than 4.5 million children in more than 5,000 schools have been using the special version of Bing ever since. Today’s roll out means any school in the US can sign-up to enable Bing in the Classroom. While Bing will remain largely the same with this custom version, Microsoft’s roll out is clearly aimed at convincing schools to move away from using Google. The search giant doesn’t offer a comparable service to counter Bing in the Classroom, but it does have special versions of Google Play and Google Apps for schools. Neither provide ad-free search though, which isn’t surprising given Google makes more than 90 percent of its revenue from advertising.