Alice and the Boa Constrictor — Laurie Adams

After learning in science class that boa constrictors make wonderful pets, Alice saves her money until she has enough to buy Sir Lancelot. There are two cliques in her class at Miss Barton's School for Girls -- the Peaches and the Turnips.  The Peaches are the more popular and Alice wants to be a Peach.  With the acquisition of Sir Lancelot, she makes a presentation in her science class and so impresses her classmates that she becomes a Peach.