Eight shapes drawn plainly and named aloud, from circle and square through to diamond and heart. Recognising shapes is the same visual skill children later use to tell letters apart, which is why shape work tends to come just before alphabet work.
Circle, square and triangle usually come first, then rectangle and oval. Star, heart and diamond tend to follow once the basic four are secure.
Telling a circle from an oval is the same discrimination a child needs to tell b from d. Shape practice builds that before letters arrive.