New ballet slippers are a treat for dancers of any age.

But that treat may come more often than expected for growing children and their parents, who suddenly find them thinking: “Didn’t I JUST buy you a pair?!”

As pre-teens and adolescents hit growth spurts, their feet may grow by a half or whole size within a school year. And for dancers taking class several times a week, the change will be felt quickly

One way of knowing when it’s time to go back for a larger pair is to simply look:

For example, Capezio’s stores are staffed with many former dancers who can help parents and children understand how a properly fit ballet slipper should feel on the feet. So then when something feels too tight, the child can know the difference on their own.

One New York dance mom says the best way to know when the shoe no longer fits is to talk to your kid.

“They know because its uncomfortable,” said Okite, who was fitting her 12-year-old daughter for ballet slippers at Capezio’s flagship store in Manhattan. “She’ll say ‘Mom I’m bending my toes.’”

One factor unrelated to growth is a student’s level of technique. As dancers advance in a school’s classes, they’re given increasingly difficult work. When that jump happens, their ballet shoes should also take a step up, from single elastics across the top of the foot (as in the Daisy, Lily and Love Ballet) to criss-crossed elastics (as in the Juliet, Cobra and Hanami) to hold the foot in for high-flying jumps and fast turns

Students who take a lot of class may find that their shoes are getting scuffed or worn, but if your little star wants perfectly clean shoes, let her or him know: Dirty still fits!

And if your studio floors see a lot of traffic, that may be a reason to invest in leather ballet slippers.

“Leather is easier to clean than canvas,” Yolanda Walmsley, who recommends breaking in a back-up pair for performances so the clean shoes are worn with a costume. “They can wear them around the house.”

Later on, the choice of leather or canvas will be a personal choice that dancers make based on their preferences for fit and cost.

One common mistake to avoid is buying a too-large shoe and expecting to grow into it.

“You don’t want too much space because that can be dangerous. A dancer could trip,” said Orekomaiya. “You don’t want them baggy. We stress a good fit for injury prevention.”

Before class, it’s also important to make sure that your child’s shoes have the right tension in the drawstrings. These thin strings will pull in some extra fabric. If there is too much excess, they can be tied into small bows and trimmed with a simple snip of a pair of scissors.

But don’t trim too much — and never remove the drawstrings. Without them, the shoe will be too loose and essentially unusable. On Capezio’s classic shoe, the Daisey, drawstrings have been tacked down so they cannot be pulled out. Additionally, Capezio’s designers have also eliminated the drawstrings on some models of ballet shoes. Which was in response to customer feedback said Orekomaiya: “Kids were pulling the drawstrings out.”

And that’s a key feature of the Love Ballet slippers and the new Hanami ballet shoes, made of four-way stretch canvas that clings to the foot — without need for drawstrings at all.