How is it schools are considered safe but family gatherings are not?

This is a common question circulating around social media. And it isn't a dumb question. But there are some answers.

Firstly, I'd like to point out that on many levels this is a compromise. And I'm not aware of any government which hasn't acknowledged this at one point or another. Which is to say that a primary reason is that even essential services cannot operate reliably when schools are closed. But, there is certainly more to it than that. Otherwise it would simply be sacrificing our children.

I point this out first however only the set the tone. This isn't a perfect answer.

Continuing on, I think it best to start with the objective reasons. And that is, studies have shown that children are less likely to spread the disease in general. They appear to be less contagious in general and contagious for a shorter period of time. Perhaps, in part to their typically lower grade symptoms.

These benefits DO degrade as the children get older. In fact, many studies show that high school students are just as good at spreading the virus as anyone else. Really, they only benefit from also being in a group which is usually asymptomatic. And this is why some places also treat older students differently. Though, admittedly this is not as consistent. But, you may live in an area where certain grades switch between in person and online learning, or where older grades are exclusively online, but younger grades are still doing in person learning.

Multi-household family gatherings on the other hand don't enjoy these benefits. Each household will have at least one adult, and possibly 2 or more. They are able to easily spread the virus between themselves and the younger family members. Also, the ratio of older to younger people is much more balanced than in a school environment which is another complicating factor.

Contact tracing is another somewhat more subjective reason, but I think that the data thus far backs it up enough to use as a point here. Schools know which students take which buses. They know which students are in classes together. And they can create cohorts to better segregate the school population. People on the other hand have been shown to be both less diligent in keeping contacts and even outright lie or hide contacts to "protect" friends or family from being forced into isolation. Schools have not been shown to have this bias.

And contact tracing to identify others who have been infected or who are at high risk is important in curbing the spread. 

Lastly on the subjective spectrum is the environment itself. And, this is subjective more because it isn't necessarily universally true. But, it certainly is true in many cases and would likely be a contributing factor. Those points are that schools are larger and typically have better air circulation. The air borne spread of the virus is much more likely when the air in rooms is refreshed less often. And schools are also following much stricter and regularly procedures on sanitation and taking active efforts to keep students and staff protected. 

While it certainly is possible that private residences are doing equal or better at these things, the numbers don't bear out that this is happening on any sort of helpful scale. More than likely, your kids actually ARE safer at school than at home or at a relatives house.