Trace pollutants through the environment in the seventh lesson of this series on the science of food. Looking at a picture of the plants and animals in an aquatic ecosystem, learners use dot stickers to represent harmful chemicals as they move from the producers through the different levels of consumers. A clear demonstration of the widespread, negative effects of pollution and the impact it has on the food we eat. Reinforce these concepts with a reading of The Mysterious Marching Vegetables, connecting science and children's literature.