In a medium bowl, whisk the olive oil with the lemon juice and season with salt and pepper. Add the zucchini and toss well; let stand for 3 minutes. Arrange the zucchini slices, overlapping them slightly, on a platter. Add the arugula to the bowl and toss with the dressing, then mound on the zucchini. Scatter the Parmesan over the top and serve.