Both teacher and student must be willing participants. A positive attitude and repeated exposure is critical for success. Remember, a real problem presents a challenge that cannot be resolved by mere recall, and an individual must accept the challenge. An exercise is a situation that involves practice to reinforce a learned skill. Teachers must include exercises, but exercises should not be confused with problem solving.
Problems often develop into exercises as skills are learned.
In the same classroom some tasks will be problems for a few students, exercises for others, and mere recall for several. There is no way to avoid this. We must simply remember to challenge all students and provide repeated exposure to problem solving throughout the year. Oh, and in case you have not yet solved the conundrum, the truck driver was walking. Great lateral thinking puzzles.