What is filtration in grade 7?

In seventh-grade science, filtration is taught as a physical method used to separate an insoluble solid from a liquid. Students learn that when you have a mixture like sand and water, you can pour it through a filter paper placed in a funnel. The tiny holes in the filter paper allow the water molecules to pass through because they are small enough, but the sand particles are too large and get trapped on the paper. The liquid that passes through is called the filtrate, and the solid left behind is called the residue. This concept helps students understand mixtures and pure substances, as well as the properties of matter. Teachers often conduct hands-on experiments where students create their own filters using materials like cotton, gravel, or coffee filters to clean muddy water. This practical application reinforces the theoretical understanding of how particle size determines whether a substance can pass through a barrier, laying the groundwork for more complex separation techniques studied in higher grades.