Cover one eyepiece of a pair of binoculars with a lens cap and face the "big" end of the binoculars towards the Sun. The uncovered lens will project an image of the Sun that can be cast onto a plain card held about a foot away. Use the focus wheel to sharpen the image.
Ideally, the binoculars should be fastened to a tripod or stand. A cardboard "collar" with holes cut to fit the large lenses will shade the card on which the image is projected.
A small telescope can be used the same way.