Final answer:
Russel's actions exemplify the investment in human capital, which involves increasing economic value through gaining experience and skills.
Step-by-step explanation:
Russel's decision to leave his job as an elementary school teacher to improve his skills in data analysis and later taking a higher-paying job at a consulting firm is an example of the concept of human capital.
Human capital refers to the economic value of a worker's experience and skills, which includes factors like education, training, intelligence, skills, health, and other things employers value such as loyalty and punctuality. In this case, by enhancing his education and skills, Russel is investing in his human capital, which in turn allows him to move to a higher-paying job, reflecting the increased value of his labor to employers.