Hello! I am teaching 4th grade Science and we are working on the body systems (digestive, respiratory, circulatory, and excretory.) I'm frustrated that we have so little time to spend on each one (not to mention the fact that it is taught in a language that the students are not proficient in, as an added difficulty.) I'm curious about how much time other teachers spend on each system, and if anyone has any effective demonstrations/experiments to illustrate key aspects. Thanks!