A unified packet among all the schools in the district, or at least all the students in a school, is a convenience for people who are worried about the summer slide. Of course, as always, the people who are most worried are the ones who have the least to worry about - children with well-educated parents gain skills over the summer because their parents do things with them that help them gain skills, put them in the sort of summer camps that, while fun, help them gain skills, and so on. It's the very poor, with the parents who are the least well educated and have the least free time and the most warehoused of day camps whose kids fall behind.

There are also summertime workbooks at any bookstore for parents who either don't get a summer homework packet or who think the homework packet is too light. Those generally have three months of math and reading comprehension worksheets with sometimes some suggested science projects as well. (I'll be honest here. Despite what I just up there said about well-educated parents, summertime homework is about the only homework I approve of for elementary school. Even if it's just two worksheets a day and a reading log it does mitigate skill loss in students who are likely to lose skills. In poorer districts the loss can add up to three months every summer, and it's not all gained back in the first month of school. Meanwhile, their wealthier counterparts have gained a month or more in that same time. And a store-bought workbook, while generally uninspired, at least is less work than running around trying to organize science projects and current events and book reports and your own math on your own.)