A person stands on top of a cliff and throws a ball with a speed of 20 m/s at an angle of 10 degrees from above the horizontal into the sea. What is the height of the cliff to 1 decimal place?

I would begin by instructing them to draw a diagram of the problem. This would be of a cliff, labelled height s_y, with an arrow representing the ball being thrown from the top. This should be labelled with the velocity and angle of projection. I would then instruct them to choose a direction for the vertical and horizontal and thus split the problem into the two planes. Then, I would advise they write down what they know in terms of the variables of motion (i.e. x/y initial/final velocity, displacement, time, acceleration) which, in this case, is u_y = 20sin10, u_x=20cos10, a_y=-9.8 ms^-2 and t_f=3s. Then, I would advise that they consider what variable they are looking for (s_y) and to find the appropriate equation of motion that includes variables that we know or can calculate. Thus, they should find that the useful e.o.m. is s=ut+1/2at² and thus obtain the final answer of 33.7m.