Pat modeling clay for each child into a smooth surface. Then allow the children to put the feet of the plastic animals into the surface of the modeling clay, to leave "tracks". Encourage children to compare the tracks left by each animal, by asking probing questions. (For example, asking if a hoof looks different than a claw.)
Show the class pictures of different animal prints. (The prints should be large enough for details to be obvious). Ask the class probing questions to get them to notice different things about each animal. The website parentingscience.com suggests asking questions like how many toes the animal has, and what sort of feet the animal must have (such as hooves or paws).
Show the class pictures of animal feet, and encourage them to guess what the prints would look like. Then show the actual prints, so the class can see what they got right. You can also make a game by showing three animal feet and three corresponding prints, and asking the class to decide which print belongs to which animal.