Assemblies are usually the only time school administrators can address all students at one time, so it is important to make the time count. Use your assemblies to engage students through fun and interactive entertainment and activities. You can promote school spirit, encourage student participation in extra-curricular activities and help students de-stress.
Ask a local junk yard to donate an old car, and paint it the colours of a rival team. Tell students to dress in old clothes, and supply paint brushes and paint in your school colours. Blow a whistle, and have students rush to cover your rivals' colours with your own. It's messy, but fun and enjoyable for all ages. You can also divide students into sections or grades and have a shouting contest or a "color rush." Assign one school colour to half the grades and another colour to the other half the day before the assembly. When everyone is seated, blow a whistle, and give the teams one minute to cover as much of the facility floor as possible with their colour. Students may use paper, blankets and even themselves.
Before a college assembly, have the students elect 10 guys to be in a male beauty pageant. During the assembly, place 10 chairs on the floor in front of the seats, and have the elected students sit. Choose five girls from the audience for each contestant, and supply them with make-up, hair products and old prom gowns. After the "girls" are ready, hold the pageant and let the audience determine the "prettiest" contestant. You could also hold an improv contest. Make enough slips of paper for all of the students who will attend the assembly, and give each a number from one to 20. Hand out the strips as the students enter. When everyone is seated, explain what improv is. Call the ones, and give them a funny cue, such as "A group of criminals being interrogated by policemen." Follow with the rest of the number groups, and choose a winner by volume of applause.
Rent a couple of karaoke machines, and have students nominate each other to sing a certain song. You can also let groups of students sign up before the assembly to sing a song together. Or, hire an illusionist to perform during the assembly. Ask her to use plenty of student volunteers. Have the school theatre troupe put on a murder mystery play, and use the student audience to help solve it. Invite a motivational speaker, and have him teach the student body relaxation and stress-reducing techniques.
Set up an obstacle course in your facility, and have students sign up in five-member teams to complete it. You can also have a team relay using silly activities like bobbing for doll body parts. You could also give your students a "Fun Day" at the assembly. Instead of staying seated, set up games and activities for them to participate in. Play music and give away small prizes to game winners. Or, rent sumo costumes, and have students sign up to wrestle at the assembly.