Moms donating their breast milk to strangers, dads taking someone else’s kids to school: Minnesotans showed a basic human impulse to look out for their neighbors.

After Chicago closed 50 schools, activists won an elected school board. As Cleveland closes 18 schools, some residents want the same.

It can handle the added heat better than existing substrates, and it will let engineers keep shrinking chip packages—which will make them faster and more energy efficient. It “unlocks the ability to ...