This diagram shows a wave diagram with several points marked with dots. There’s an orange dot where the wave meets the baseline. Next, there’s a green dot where the wave reaches its highest point. Next, there’s a blue dot where the wave meets the baseline again. Finally, there’s a purple dot where the wave reaches its lowest point. Each of these coloured dots corresponds to a simple coloured circle containing an arrow pointing in a particular direction. The orange circle (wave meets baseline) has an arrow pointing to the right. The green circle (highest point) has an arrow pointing up. The blue circle (wave meets baseline again) has an arrow pointing left. The purple circle (lowest point) has an arrow pointing down.