The CD player is switched on and a mellow male voice singing a pop tune fills the hot and humid school gymnasium, seeming to soften its ambience like a breath of fresh air.
On stage, a woman in an oversize T-shirt and baggy pants calls out through a wireless mike to the roomfull of excited students kitted out in their sports gear: "Okay, let's dance to the music now! Forward/ forward/ side/ side/ zoom/ clap/ zoom/ clap."
"Forward," "side" and "clap" — no problem understanding, there. When it comes to "zoom," the kids — who are dancing with their feet wide apart and their arms out at their sides — instantly swing their right arms round like a boxer trying to land a big punch. Then the next moment, they clap, punch again, and clap.