I keep a set on a small binder ring, and use them frequently with my 3 year old. In fact, she was actually around 18 months when I started using these to build her language and vocabulary. We've began working on association; pairing cards that are relevant to one another. For example, finding all the cards that have to do with Winter time.
Each card measures 3.5 x 6", bordered in bright polka dots, large black text, and a colorful graphic to match the word. Perfect for visual learners!