Once a link becomes popular, school IT departments often add it to their blocklist. If this happens, your other options are to use a VPN or web proxy.
version 1.5.2 is often played "unblocked" at schools or workplaces through Eaglercraft
Be aware of your local institutional policies. Playing games on monitored networks can result in disciplinary action if caught by IT administrators. Maximizing Performance on School or Work Devices
He turned the Chromebook slowly.
A VPN encrypts your internet traffic and routes it through an external server. This prevents the school router from seeing that you are trying to connect to Minecraft services.
minecraftforfreex.com – Offers Eaglercraft (1.5.2) and other browser-based versions.