A school book of condolence has been opened for teenager Rebecca Aylward as police continue to question two 15-year-old boys about her murder.
South Wales Police have been given an extra 36 hours to hold the boys, which continues until early Wednesday.
Rebecca, also 15, from Maesteg, was found with head injuries in woods in nearby Aberkenfig on Sunday morning.
She was at Archbishop McGrath Catholic High School, which has opened during half-term to offer support for pupils.
The schoolgirl, described by her family as "happy, outgoing and bubbly" failed to return home after being dropped off to visit a friend on Saturday.
She was last seen in Sarn Hill, Sarn, near Bridgend, at about 1230 BST on Saturday.
Police are desperate to speak to anyone who saw her after that time or spoke to her on a phone.
Her body was found at about 0900 BST on Sunday.
The results of a post-mortem examination found she had died as a result of head injuries.
South Wales Police said it would use "every snippet" of information to catch her killer.
The 36-hour extension granted to police to continue questioning the two boys runs out early Wednesday morning. This can be extended by a magistrates' court up to a total of 96 hours.
In a statement issued via the force her relatives said: "Rebecca, also known as Becca, was dearly loved by all her family.
Bridgend council mobile youth workers are approaching young people to make them aware of the support services in place.
The local authority's "Just Ask" bus, a mobile resource that provides confidential advice to young people, is also in the Aberkenfig area.
"She will be sadly missed, she was a very happy young girl, she had an outgoing and bubbly personality.
"As a family we are all devastated by her untimely death and wish to be left alone to deal with our grief in private.
"Becca can never ever be replaced."