Unit 3 Final Project: Shooting Game Not Scoring

My student is creating a shooter game for his final project and we were able to get the bullets to shoot, but we cannot get it to score or change the animation. We’ve tried everything. Please help.

your redeclaring your group variable within the bullet scope

function fire() {
  var bullet = createSprite(jet.x, jet.y - 50);
  bullet.setAnimation("bullets");
  bullet.velocityY = -25;
  bullet.lifetime=100;
  bullets.add(bullet);
}

by using bullet instead of bullets you can successfully add the bullet to your sprite group to use for collisions such as .collidewhich is what you seem to be checking to make sure the bullets hit.