Grade 4 and up. An exciting introduction to hands-on investigation in environmental science using procedures similar to those employed by professional scientists worldwide. Study unit is complete with everything a teacher needs to lead a group of up to 50 students through a detailed study of water quality in a lake, stream, pond, or aquarium. Each student collects water samples and makes measurements of pH, dissolved oxygen, nitrate, and ammonia using foil-sealed reagent tablets. Lecture materials, illustrated handouts, teacher tips, student instructions, data sheets, and student activity worksheets are included. Refill includes foil-sealed reagent tablets.