I need help completing an assignment in response to the following prompt: First complete this sentence with appropriate names/words of your...

This prompt is obviously based on Franz Kafka's story "The Metamorphosis" in which the protagonist, Gregor Samsa, wakes up to discover that he has been transformed into a giant insect. The point of the exercise is one of controlling perspective, and understanding how a character's interactions with the world are determined through not only individual choices but through how others view that character. 

One of your first choices, perhaps even before that of the creature into which the character is transformed, is gender. The character can have a traditional male or female identity, or perhaps some more fluid or transgender identity. Choosing a traditional gender identity makes controlling pronouns in your writing much easier, but it restricts some of the imaginative possibilities for using this species transformation to also interrogate the nature of gender.

Your next choice will be type of creature. Your decision in this case should rest on whether you want a sort of magical realism in which everything but the initial premise of the story is real or whether you want to move into some sort of fantasy world. In the first case, if everything but the premise is realistic, you might choose a cat or dog, perhaps having the protagonist's consciousness moved into that of the pet. More imaginatively, you could choose a mouse or cockroach, where the change in size would make every aspect of the setting function quite differently; to an ant for example, a shoe would be as large as a house is to a human. Alternatively, you could choose a fantastic creature, invented entirely our of your own imagination, or a mythic one. In the case of a transposition into a fantastic creature, the home environment and other creatures in it might also be transformed. You could, for example, have your character fall asleep playing a video game and awake inside the game universe, transformed into a dragon or a Pokemon. 

Technically, you would want to use the character's experiences to show how the species change affects the way the character interacts with the environment rather than just telling us how the character has changed. How you handle this involves deciding whether the character has been given species-appropriate instincts or not. For example, if your person became a cat, the person would either wake up with the skills and knowledge of an adult cat (how to jump, pounce, kill small rodents, etc.) or would struggle to figure out four-legged locomotion. The character would have different senses -- perhaps a more acute sense of smell and weaker color vision -- and interact with the furnishings differently. A cat or dog would need to jump up to a bed rather than sit down on it, while a gecko might feel most comfortable hanging upside down from the ceiling. Rather that telling us about the creature, you should show us how the creature interacts with an environment.

Especially given the Kafka parallel, this assignment seems geared towards creating a creature that cannot speak or use other modes of human communication. You would then want to think about how the person would wish to attempt to communicate or not in the new form based on whatever backstory you create for the person. For example, an abused wife or daughter might delight in the new identity as an opportunity to escape a bad situation, a curious teen might enjoy being a cat, while a single mother might be frantically worried about how to take care of her child in creature form. Thus your initial interactions should not be conditioned just by the nature of the creature but also by the character of your protagonist and the protagonist's relationship with the other person.