I really like soft blocks for infants and toddlers. Often, these are designed so they fit directly into the small hands of the youngest children. They can get them into their palms and then directly into their mouths for easy exploration. The ones below are also made in a safe plastic, so they can be easily washed either by hand or in the dishwasher.
These can be piled up, lined up, knocked over, and thrown about. They are created so that providers and parents can label them and encourage language, especially mathematical language. Using words like “blocks” and “squares” encourages spatial thinking language. Using color words encourages categorizing. Using words like “more” and “less” and “1, 2, and 3” encourages number and quantity. These blocks are a great infant manipulative.