Lesson Plan 12 - ABC - Australian Broadcasting …

1 Lesson plan 12 Salt and germination Brief description This fascinating, cheap and very reliable experiment clearly demonstrates the damaging effects of salinity (salt) on seed germination . Mung beans are germinated on paper towels in takeaway containers using various concentrations of salt water. The activity captivates student interest and results are clearly visible within three days. Use it as part of a unit on plants or Australia s salinity crisis. * Readily available from supermarkets and health food stores Duration: 80 - 145 minutes (total over 3 to 7 days) Year level: Lower to upper primary Topics: Plants, germination , salinity Preparation: 10 to 20 minutes Extensions: SOSE: Investigate Australia s salinity crisis Overview SESSION 1: DISCUSSION AND PREPARATION (50 70min) Introduce the experiment Discuss procedure Prepare salt solutions Distribute materials and prepare Petrie dishes Add mung beans to Petrie dishes and store in cool location OBSERVATION SESSIONS (over 3 to 7 days) (10 15min) Record the number of beans that have sprouted Record any other observations that can be made CONCLUDING SESSION (20 30min) Record the number of beans that have sprouted Record any other observations that can be made Analyse the and present the results using age appropriate instruments (eg tables, graphs, posters) Lesson 12 germination Experiment Page 1 2006 | ABC Science Online Materials and equipment Qty / Student Description 201 Mung beans (dry)

2 12 Round takeaway container (lid optional) 2 Paper towels 1 Cling wrap (~ 15 cm piece) 1 Rubber band 1 Packet of salt 13 Distilled water for salt solutions 1 Measuring jug or beaker 1 Plastic cup 1 Eyedropper for adding salt solution 1 Kitchen scales for measuring salt 1 Tweezers (shared) 1 Magnifying glass (shared) 1 One 500 gram packet of dry beans is sufficient for the whole class available from health food stores and some supermarkets 2 Small and large containers are suitable 3 Salt solutions prepared by teacher or group see Teacher Notes Page 7 Preparation Purchase mung beans from supermarket or health food store.

3 Collect sufficient quantities of takeaway containers, plastic cups etc listed in the table above. Decide how you will allocate salt solutions to each students (see Teacher Notes P. 8). Lesson 12 germination Experiment Page 2 2006 | ABC Science Online Objectives Students prior knowledge No prior knowledge is required or assumed for this Lesson plan . The objectives listed below are suggestions only and may not be appropriate for every year level. Science skills Students will: Carefully prepare and label a Petrie dish (takeaway container) for the germination experiment Carefully add salt solution and mung beans to Petrie dish Observe the mung beans over several days Record their observations using a table in their science journal Infer that high concentrations of salt prevent seeds from germinating Science concepts Low concentrations of salt are naturally present in soil and water High concentrations of salt are naturally present deep underground in Australia European farming practices, which removed or replaced native plants with crops that have shallow roots, have raised groundwater and brought salt to the surface High concentrations of salt in the soil or water prevent seeds from germinating and plants from growing Seawater has a salinity of approximately (approximately 35 grams of salt per kilogram of seawater)

4 Positive attitudes Students will Develop an appreciation of and concern for the environment and the environmental impact of farming practices Develop a sense of wonder about the amazing process of plant germination and growth Develop an understanding of and appreciation for the scientific method in investigating real life problems Work cooperatively with partners/group members and ensure handle all equipment and water carefully and responsibly dispose of waste responsibly (eg pour waste water onto plants or garden beds instead of down the sink) Lesson 12 germination Experiment Page 3 2006 | ABC Science Online Procedure SESSION 1 DISUCSSION & PREPARATION (50 to 70 minutes) Introduction Whole Class (10 15 min) Discuss the salinity crisis in Australia see Teacher Notes (P 10) for a brief introduction and / or: Distribute dry and soaked mung beans (two each per student) to observe and lead a discussion about germination and the life cycle of seeds.

5 Students will observe a scar and tiny hole in the mung bean seed coat. Discuss the amazing fact that each mung bean seed contains all the energy and instructions required to create a whole new mung bean plant which, under the right conditions, will grow and produce more mung beans. Discuss the objectives of the Mung Bean germination experiment to determine the amount of salt mung beans can tolerate before failing to germinate. You could use the discussion to develop the procedure together with the class by asking leading questions such as: how could we find out how much salt mung beans can tolerate? how much salt should we use? can we use plain old tap water? does it have any salt already in it? Each student will prepare a Petrie dish with paper towel, salt solution and mung beans. Failure of a seed to germinate is just as important as a successful germination .

6 Prepare salt solutions as a demonstration Whole Class (10 15 min) Students will appreciate just how the tiny the quantities of salt the mung bean seeds can tolerate if they see the actual amount of salt being added to the water, so if possible, perform it as a demonstration you can involve them in the calculations by writing them on the whiteboard or simple by discussing each step. Using the kitchen scales, plastic cups, salt and distilled water, prepare salt solutions of various concentrations for the class to use discuss the procedure and perform calculations together with the class if appropriate (see Teacher Notes P 6 for details) Allocate groups, discuss safety issues and distribute worksheets and materials Prepare Petrie Dishes Individual Groups (20 25min) Group manager collects materials Investigate dry and soaked mung beans with magnifying glass to identify parts Each student prepares a Petrie dish with paper towel and a label Moisten paper towels Place beans on paper towel Store beans in a bright, cool place away from direct sunlight Conclusion Whole Class (10 15 min)

7 Discuss student predictions set science journal writing tasks Lesson 12 germination Experiment Page 4 2006 | ABC Science Online Procedure continued .. OBSERVATION SESSIONS (3 to 7 days 10 to 15 min each) Observe and record results at approximately the same time every day students will be very keen to check progress often so it is worth discussing the importance of recording the results at the same time (ie regular intervals) Each student counts the number of beans that have sprouted in the Petrie dish they prepared and records the number in their science journal CONCLUDING SESSION (20 30 minutes) Once all the results have been recorded, calculate the average number of beans that have sprouted by the end of each day (the results are easier to interpret if the total numbers sprouted are recorded everyday eg if three have sprouted on day 1, record 3 / if 6 more sprout the following day record the new total of 9)

8 Calculate the averages for each salt concentration tested (if appropriate, students can perform these calculations if not, perform them on the board) Discuss the results and important observations from the experiment such as: Mung beans will not germinate and grow if water salinity exceeds approximately The salinity of seawater is approximately so the salt tolerance of mung beans is much less than half that of seawater salinity levels Discuss the experiment and whether the method answered all of the students questions if not, discuss what changes could be made or other ways the questions could be answered, and if possible, follow some or all of these up Lesson 12 germination Experiment Page 5 2006 | ABC Science Online Teacher s notes Preparing salt solutions Perform this a teacher demonstration for younger students or to economise on time.

9 Teaspoon Small cup (for salt) Measuring cup (250ml or larger) Accurate kitchen scales Plastic cups or bottles Table salt Distilled water 1. Equipment and materials: 2. Measure salt required into cup on scales (see table below for amount to use) If the weight required is less than your scale s smallest increment, measure out 2 or 4 times the amount, pour into a pile and use a spatula to halve or quarter the pile as illustrated. 3. Add salt to measured volume of distilled water and stir Repeat for each of the concentrations required as per table below Amount of salt to add (in grams) to demineralised water (in millilitres) for various salt solutions Grams of salt to add (s) Salt concentration (c) (by weight*) 250ml 500ml Tap 0g 0g 0% 0g 0g (equiv.)

10 To seawater) salt to add = concentration weight of water ( 1 concentration) s = c W / ( 1 c ) [* Note: 1 ml of water weighs 1 gram] Lesson 12 germination Experiment Page 6 2006 | ABC Science Online Preparing Petrie dishes Each student can prepare their own Petrie dish, add a label (see below) and salt solution. Share scissors and pens if necessary. It is advisable to check each Petrie dish before allowing students to add salt solution to ensure labels match solutions added and guarantee clear experimental results. Use the Petrie dish (takeaway container) to mark a circle on the top sheet 2. Cut paper towel into circle 1. Fold two sheets of paper towel in half two times to produce a square eight sheets thick Use an eyedropper or pipette to moisten paper towel drain off any excess water 3.