This can be done in two ways depends upon your usage..
1)if you use browser back in addNewStudent.html to go to school.html.Better to use cookie concept. For ex: when going to addNewStudent.html from school.html setcookie("tabchange","tab2") when coming back from addNewStudent.html to school.html(onload of school.html check whether the cookie exist or not,if exists depends upon cookie enable your tab);
2) if you use any button or link in addNewStudent.html to go to school.html.Better to use queryparams. for ex: pass tabchange queryparam for school.html to addNewStudent.html?tabchange=tab1 get that queryparam from addNewStudent.html and assign to link or button your as href="/school.html?tabchange=tab1" after clicking that button onload of school.html get the queryparam and enable the tab..