1. The problem statement, all variables and given/known data I am a teacher currently teaching very introductory physics. I just came across a test question asking the students to choose whether acceleration is vector or scalar. 2. Relevant equations 3. The attempt at a solution I have always thought that acceleration can be either vector or scalar. For example, we call 4 m/s a "speed", and 4 m/s west a "velocity". Similarly, 10 m/s2 is scalar while 10 m/s2 west is a vector, but they are both just called "acceleration". Am I wrong? Thank you in advance!