This experiment uses a laser to determine the focal point of a curved mirror on its concave surface.
On a piece of paper draw a line which will be your principal axis. Place the mirror at one end of this line so that the centre of the mirror bisects the line.
Use the laser to shine a ray of light parallel to the principal axis so that it reflects off the mirror. Using a sharp pencil mark the path of the ray on the paper.
Repeat this for a number of different starting positions - the point where all the lines cross the axis is the focal point of the lens.
It should be noted that there are risks using lasers. Care should be taken to choose a laser which is eyesafe at the aperture and to be careful with the laser alignment so that stray reflections are minimised.