Bring in meals from the school cafeteria.
Which do you think is healthiest/least healthy? Why? What makes a meal healthy? How can we tell?
What information do we need to solve this problem?
Talk to school management discussing their reasons for each meal option and/or
Make posters to help other students make healthy choices
Look at how nutritional needs change for athletes. How could we show this on our posters?How could we change these meals to make them healthier (may use: http://healthyeatingclub.com/info/articles/nutrients/food-source.htm)?
If you feel the need to convince your pupils about the importance of nutrition, this video does a pretty good job