In this essay, I examine the concept of thinking in Hannah Arendt's writings. Arendt's interest in the experience of thinking allowed her to develop a concept of thinking that is distinct from other forms of mental activity such as cognition and problem solving. For her, thinking is an unending, unpredictable and destructive activity without fixed outcomes. Her understanding of thinking is distinguished from other approaches to thinking that equate it with, for example, problem solving or knowledge. Examples of a "problem-solving", skills-based approach to thinking that place a premium on behavioural change are drawn from the context of the prison. I offer an alternative example of thinking with others from my philosophy classes in the prison. I draw upon Arendt's insights to develop a concept of "thinking-in-concert". Whilst Arendt believes that thinking must be a solitary activity, I argue that the concept of "thinking-in-concert" helps to capture experiences of thinking with others in a manner that is more hesitant and provisional than some descriptions of communities of enquiry or democratic education. The embodied presence of others matters when "thinking-in-concert". I describe this approach as educational as well as conversational. This helps to communicate the way in which we turn towards others and may be pulled up short by them as we strive to think together or experience moments of conversion or insight whilst enjoying the ordinary activity of talking with others. This concept may help us to understand the difference between the experience of thinking, teaching and learning when we are physically present to one another and the experience of virtual learning or teaching.