Summary Drip water on leaves to see how leaves are waterproof and shaped to direct rain water off the leaf. Compare with other surfaces. Science content Biology: Features, Adaptations of Living Things (K, 1, 3, 7) Biology: Food Webs, Ecosystems, Biomes (3, 4) Lessons activity is in Water and rain Tropical Rainforest Plants: comparison with our native plants Materials either leaves on plants outdoors or leaves on a branch brought indoors and duct-taped to the edge of a tray in a natural position dropper bottles filled with water, that can dispense a drop at a time e.g. empty food colouring bottle for demonstration: clothing types that absorb water rapidly or make it bead up on their surface Procedure If possible, take students outside to a place with bushes. Give them each a dropper bottle filled with water and a worksheet. Ask them to drip individual drops on leaves and watch what happens to the drips: First compare how quickly the water soaks into the leaf compared to their clothing made of different fabrics. Then if the water runs off the leaf, draw the path of the water for different leaf shapes, then . Record on the worksheet. Indoors, tape cut branches into trays so that they hang over the tray. Students drip water onto the leaves and watch where the drips go, and whether they soak in. Record on a worksheet. Outside or indoors, give students modelling clay, to mimic heavy snow. They wrap the clay around stems to see if the stems bend or break. Discussion of discoveries: Usually dripped water stays as a drop, and flows off the leaf via the pointed drip tip (if the leaf has one), sometimes after it has fused with other drops. The drops do not soak into the leaf. The drip tips divert water off the leaf, so that bacteria and fungus does not have a place to grow. The waxy coating forms a physical barrier that resists penetration by virus particles, bacteria and fungi. It also prevents water loss from the leaf. Evergreen plants have an especially waxy coating, to prevent water loss through the winter, when the ground is frozen and the plants are not able to access liquid water. Our evergreen natives such as cedar, salal and oregon grape will bend when weight is added to their stems. They are able to carry snow without snapping. Other natives, such as salmonberry, snap with the weight, but they lose their leaves in the winter and so the snow will not build up on them so much. Attached documents plant_features_worksheet.pdf Biomes worksheet drip tips and bendy.pdf Notes Not sure that temperate rainforest leaves have technical drip tips. Most leaves in all biomes of the world have some kind of a point at the end which directs water off the leaf, but our temperate rainforest leaves don't have a particularly pointy or long tip (whereas tropical rainforest leaves do). Cedar is a little confusing with the water drops, as they tend to go between the scales, looking like they have soaked in. Maybe use only wider leaves? Grades taught Gr K Gr 1 Gr 2 Gr 3 Gr 4
