Characteristics of Drought The hands-on experience of planting drought tolerant plants is the highlight of this informative activity. Students will first be given an overview of California native plants. A comparison will be made between drought tolerant plants and water thirsty plants. Students will observe models of different irrigation systems and how each is selected for different plant types. Finally, students will be given the opportunity to plant a drought tolerant plant to take home and nurture!
Pre-Event Activities Characteristics of Drought Carrot Dissection Pre-Event Activity The purpose of this activity is to encourage students to observe carefully, to record data, and begin to identify characteristics of a Taproot. Vocabulary Osmosis: Travelling from an area of greater concentration to an area of lesser concentration through a semi-permeable membrane Diffuse: Spread out from a source Turgor Pressure: Pressure exerted by water inside the cell against the cell wall. No more water can fit. This condition is called Turgid. Transpiration: Condition in which the stomata on the leaf release excess water. This is different from evaporation because it can only take place in the leaf of the plant. Evaporation: This is a condition in which water is released to the air from a source such as soil, canopy, water bodies, etc. Phloem: Food is transported from the leaf and stem through phloem tubes. Xylem: Tubes that carry water up the plant. Materials Needed: Carrots cut in half lengthwise Carrot slices Diagrams of external and internal carrot Key for external and internal carrot anatomy Taproot: The largest, most central, and most dominant root.
Pre-Event Activities continued Characteristics of Drought There are several types of roots in the Plant Kingdom. The main function of the root is to anchor the plant in the substrates and help the plant obtain water. Plants known as high water use such as lawn grass have a root structure called a fibrous root. Fibrous roots absorb water through clusters of small wiry strands. Each strand has a network of smaller strands called root hairs. Root hairs draw in water and pass it on to the root cluster to be used by the plant. Plants known as low water use or drought tolerant have a singular main root called a Tap Root. Tiny root hairs attached to the taproot extend into the substrate and draw in water. 1. In this activity, students will work with a partner. Pass out a carrot half and slice to each partner team. 2. Each partner will draw, observe and label the parts of the external carrot anatomy. 3. It is important that observations are made before labeling the drawing. Be sure to observe the tiny root hairs as they extend from the taproot. 4. Repeat the same procedure as you observe the internal anatomy of the carrot 5. Each partner will take turns locating the specific parts of the external and internal carrot. 6. Next draw the carrot slice, paying special attention to the various layers. Locate and label the parts of the slice (cross section) 7. Each partner will take turns locating the specific parts of slice (cross section) After completing the activity, spend time going over the new vocabulary terms xylem and phloem. These are very important in the transport system of the carrot. Water is transported from the root to the stem and leaf through xylem tubes. Food is transported from the leaf and stem through phloem tubes. Xylem tubes carry water up and phloem carries food down.
Pre-Event Activities continued Characteristics of Drought How Do You Calculate the Surface Area of a Leaf? Problem: What is an easy way to calculate the surface area of a leaf? Hypothesis: If you trace a leaf on a measure surface (graph paper), then you can determine the surface area of the leaf because the traced measured surface will equal to the actual surface area of the leaf. Steps: 1. Select a leaf 2. Place the leaf on the graph paper 3. Carefully trace the outline of the leaf on the graph paper 4. Label the leaf on the graph paper (A, B, C, D, E) 5. Use the scissors to cut out the traced leaf 6. Glue the traced leaf on the data chart 7. Count the number of complete squares on the traced leaf 8. Record the number of complete squares and place a + for the partial squares Materials Needed: Different sized leaves Pencil 1-cm grid graph paper Scissors Glue stick Data chart **Attach traced leaf on the data chart (located at the end of this activity) and record the surface area measurements for each leaf.
Calculations for Surface Area: Small Leaves: Surface area of small leaf X Number of leaves in bag = Medium Leaves: Surface area of medium leaf X Number of leaves in bag = Large Leaves: Surface area of large leaf X Number of leaves in bag = Surface Area Conclusion: 1. Based on the raw data that you collected, what relationship exists between surface area of a leaf and rate of transpiration? 2. In a drought tolerant environment, which leaf type would have a greater chance of survival? Explain why? Extension: Repeat the experiment with leaves coated with petroleum jelly. How does the data differ from the original experiment? Explain why?
Pre-Event Activities continued Characteristics of Drought Leaf Chart Pre-Event Activity The purpose of this activity is to encourage students to observe carefully, to record data, and to begin to identify characteristics of water-efficient plants. 1. Ask students to bring leaves from home and/or collect leaves that have fallen off of trees on the school playground. 2. Divide the class into 5 or 6 groups. The students share their leaves, numbering each leaf with a small piece of paper or an adhesive dot i.e. Leaf #1, Leaf #2, etc. 3. Explain the Leaf Chart carefully, before students begin to record their data. 4. Brainstorm a list of describing words for each characteristic: Color: List many different shades of green or other leaf colors. Water-Efficient Characteristics: If the leaf is not a small leaf, have students specify what size the leaf is. Brainstorm a list of size comparison words or descriptions. Shape: Leaves have many different shapes. Brainstorm a list of shape words. Leaves also have a variety of edges. Feel: Emphasize the water-efficient characteristics of waxy and hairy. 5. Encourage students to record specific descriptions and to work with a partner. Materials Needed: Leaf Chart Leaves from home or playground
Pre-Event Activities continued Characteristics of Drought How to Measure and Observe Transpiration Problem: How can you measure and observe the amount of transpiration in leaves with different surface areas? Hypothesis: If you place a plastic bag over plant leaves, then you can measure the amount of transpiration, because the water from transpiration will be contained in the bag. Steps: Materials Needed: Plants with leaves the that have small, medium, and large surface areas Zip lock freezer bags Masking tape Light source (sunlight conditions will vary) Timer (to use if you are not measuring in hours) Data Chart (found at the end of this activity) 1. Obtain a plant with small surface area leaves. 2. Carefully place the zip lock bag over the leaves. 3. Be sure to create a tight seal over the leaves using the masking tape over the petiole. 4. Be sure that the soil is moist 5. Allow the set up to remain untouched for 72 Hours. 6. After 24hrs make observations and if possible take an image of the specimen to add to the data chart. 7. Observe the amount of water collected and sunlight conditions and surface area of the specimens. For SA information: calculate the SA of one lead and multiply by the number of other leaves. Record on the data chart. 8. Refer to the lab activity: How to Measure Surface Area of a Leaf 9. Repeat the same procedure after 48 hours and 72 hours. 10. Repeat the experiment with the remaining leaf types.
Pre-Event Activities continued Characteristics of Drought Transpiration Conclusion: Based on the data collected, rank the sample leaves in order of surface area from greatest 5 to least 1. Leaf Sample Surface Area Rank Based on the collected data, explain which leaf sample would have the greatest rate of transpiration:
Post-Event Activities Characteristics of Drought Post Field Trip Suggestions 1. Expand the leaf chart with leaves students bring from different areas: the desert, mountains, coastal areas, etc. 2. Art Projects: Leaf rubbings (using tissue paper and crayons); leaf prints; leaf sketches. 3. As a class or individually, students can visit a garden that specializes in drought tolerant plants such as Rancho Santa Ana Botanical Gardens or the CBWCD Water Wise Demonstration Garden. Explore the varieties of plants, leaf shapes, flowers, and other features of these plants. 4. Visit www.sunset.com/garden/climate-zones to learn more about the climate where students live. Discuss rainfall and weather in this area; based on this discussion, ask the students why they might want to have drought tolerant plants in their yards versus more traditional grass or high water use plants. Ideas adapted from Water Conservation Garden Activity Book (Western Municipal Water District of Riverside County) and Science in Elementary Education by Peter C. Gega. (See Resource List.)
SURFACE AREA DATA CHART TRACED LEAF SAMPLE A Surface Area TRACED LEAF SAMPLE B Surface Area TRACED LEAF SAMPLE C Surface Area
TRACED LEAF SAMPLE D Surface Area TRACED LEAF SAMPLE E Surface Area
TRANSPIRATION DATA CHART SMALL LEAVES Amt. Surface Area Sunlight Conditions Duration Time T-1 Start the Experiment Observations After 24 hours T-2 24 hours After 24 hours T-3 48 hours After 72 hours T-4 72 hours MEDIUM LEAVES Amt. Surface Area Sunlight Conditions Duration Time T-1 Start the Experiment Observations After 24 hours T-2 24 hours After 24 hours T-3 48 hours After 72 hours T-4 72 hours LARGE LEAVES Amt. Surface Area Sunlight Conditions Duration Time T-1 Start the Experiment Observations After 24 hours T-2 24 hours After 24 hours T-3 48 hours After 72 hours T-4 72 hours