This study is empirical research about alternative ideas on the concept of force for five different age groups, primary school students (11), middle school students (15), high school students (17), students of the Department of Primary Education (21), and active teachers in primary education (27-50). We used the same questionnaire for all groups, which shows a relationship with the answers depending on their age. The analysis of the percentage of the correct answers concerning the age of subjects gives a sigmoid curve, which is the learning curve on the concept of force. For all the questions, there was a statistically significant correlation with age. That provides us with interesting information about the teaching of the force. In particular, our results suggest that the alternative conceptions of students and teachers, reflecting misconceptions and preconceptions, reduce with age or equivalently with the education level. Our study can be used in science teaching classrooms, on the design of curricula, and teachers' professional development.