Eh, this is quite a basic shapes question lah! You teaching your little one about circle, triangle, and square? My kids learned this around age 3-4, usually through play and pointing out things around the house, like the pizza is triangle, the plate is circle, that kind of thing. A few of us mums swear by letting them trace and play with actual shape toys or do simple colouring activities, much more fun than just staring at pictures online!