My kids still learned stuff and had assignments/homework.
Even on the last day of school, although they had just fun activities, my daughter (who just finished 4th grade), they had a science test. And in the last 2 weeks of school, they had 2 research projects and they had to do a presentation with each one.
My son, who finished Kindergarten, still learned stuff and they had their usual routine everyday too. Although they also had class parties and end of school activities.
My kids go to public school.
Your child is in 3rd grade: so I would HIGHLY suggest, that your daughter practice the multiplication table, math facts, and doing addition and subtraction with 3 number digits, and also fractions. As in, fraction equations. Also practice word problems.
In 4th grade, my daughter learned algebra. And it was expected that they KNEW their multiplication table, already upon entering 4th grade. In 4th grade, the academic expectations takes a leap. So beware.
Have her practice it over the summer.
OR... use this: www.khanacademy.org
It is FREE. And it is for any kid at any age. And for adults. This site is great for math. And even Bill Gates is a fan of it. My kids use this site to practice math.