Responding when a teenager gives one-word answers but seems otherwise fine

I ask my teenager how school went and get ‘fine.’ Ask what they did with friends and it's ‘nothing.’ They're otherwise cheerful, keeping up with responsibilities and chatting normally when they choose the subject. I don't want to turn ordinary teenage privacy into a crisis. Have you found that talking during car rides, cooking or shared activities works better than direct questions, or is giving some silence the right answer?