1. Cell biology: plant cell structures (chloroplast, sap vacuole, cell wall), cell function matching (nucleus, cytoplasm, mitochondrion), organelle comparison between plant and animal cells 2. Earth–Moon–Sun system: gravitational force in orbit, tidal force explanation (alignment and height variation), model prediction strengths and limitations 3. States of matter and particle models: substance identification (vacuum, air, water, alloy), vacuum properties (no particles), alloy definition and advantage over pure metals 4. Classification using keys: dichotomous key application to identify leaf shapes (spruce, maple, holly, oak, walnut) 5. Energy: energy types and transfers (chemical, sound, heat, electrical, light), wasted energy transformation (dissipation) 6. Gas tests: identification of oxygen (relights glowing splint) and carbon dioxide (limewater turns cloudy), controlled investigation plan