Impressionism gives you an impression of the subject...not a photo like representation. Monet used color sunny warm happy colors. Subject matter was generally happy ...people at gatherings,,loved ones and landscapes. Look at examples of his work...you will be able to see.
Also color was applied in somewhat blotchy ways and not necessarily blended in ( you eye does that). You need to study some of his art and pay attention. I do not know what the criteria of you assignment was but you could draw a still life....some flowers, fruit bowl, candle sticks and use that pastels and use a loose way of drawing, apply colors as true as you can. Do your best.
Do check out his art and that will help you figure out how to draw it.