When one’s electronic infrastructure isn’t working (battery, device, network, ISP, power), or when one wants a trusted familiar well-edited source that doesn’t require a subscription or login to get all the content, or when one prefers to use paper, or doesn’t want the possibility of what you looked up being tracked and recorded, or one doesn’t want to be charged for such services, or when the device is being used by others for other things (as a phone or the other 10,000 things those devices do) or when the teacher made you turn off your devices or confiscated them.