"to appeal" や "to urge" は「訴えかける」と言い味を表します。
"to ask" や "to request" も言えます。
"A teacher urged students to ~" 「先生が生徒に〜と訴えていた」
"A teacher appealed to students to ~"
"A teacher asked students to ~" なだもいえます。
"The school's unofficial website was going viral because there was a lot of slander, and at a school assembly a teacher appealed to the students to come and tell the truth about who did it."
「学校のunofficial websiteが流行ってて、誹謗中傷が沢山あり、全校集会で先生が生徒に誰がしたか正直に言いに来いと訴えていた。」