Science 8

Optional Unit: Plant Growth

Unit overview

Plants are essential to life. Not only do they supply oxygen to the air and act as the base of many food pyramids, but in Saskatchewan, they are an integral part of the economic base of the province. How much oxygen do plants produce? Why do some plants grow more quickly than others? Why won't some plants grow at all in Saskatchewan? If using fertilizers helps plants grow, will using more fertilizers help them even more? How does saline soil inhibit plant growth?

These are some of the questions which can be considered during this unit. Encourage your students to go beyond the information in the resources and the bounds of the classroom walls to find out about plant growth, and the importance of plants to our lives.

Science writing and reading activities, as discussed in this Guide, should be incorporated into each lesson. Writing in personal reflective journals, reading from newspapers, and

reporting on the activities of science class in various formats such as essays, newspaper articles, posters, and letters are strategies through which students may refine their understanding of the concepts of science and develop their ability to communicate through the written word.

Science challenge, as described in this Guide, is meant to extend students' critical and creative thinking abilities in the context of the science concepts being studied. Activities involving science challenge should be incorporated into science lessons in each unit. The challenge is intended to give each student a chance to investigate an area of interest in more depth than would be possible for all students in a class to do. Science challenge is a key strategy for bringing the Adaptive Dimension to the classroom, and for encouraging independent learning. Investigating how varying one factor influences plant growth is a science challenge activity.

Factors of Scientific Literacy that should be emphasized

• A2 historic
• A3 holistic
• A5 empirical
• B4 organism
• B9 reproducibility of results
• B16 system
• B18 population
• B20 theory
• C1 classifying
• C11 controlling variables
• C13 formulating models
• C14 problem solving
• C16 designing experiments
• D3 impact of science and technology
• E2 using natural environments
• E13 using quantitative relationships
• F4 valuing natural environments
• F6 consideration of consequence
• G2 confidence
• G5 avocation

Concept development

• grade 1
  • characteristics and basic needs of plants
• grade 2
  • conditions important for optimum plant growth
• grade 3
  • adaptive nature of plant structures
• grade 4
  • diversity of plant species
• grade 5
  • functions of specialized plant tissues and organs
  • the place of agriculture in Saskatchewan
• grade 6
  • plant response to external stimuli
• grade 7
  • consideration of plants as living organisms
  • how plants are adapted to the Saskatchewan environment
• grade 8
  • how plants alter the abiotic and biotic conditions they encounter

Foundational and learning objectives for Science and the Common Essential Learnings

1. Explore the factors which influence plant growth .
   1. Identify factors important for plant growth.
   2. Classify factors as external or internal to the plant.
   3. Consider the ease of regulation of growth factors.
   4. Investigate methods of manipulating factors.
   5. Design and conduct experiments to compare effects of alteration of growth conditions.
2. Understand the relationship between plant growth and agricultural practice.
   1. Examine the effects of irrigation on both plants and soil.
   2. Explain how fertilizers and herbicides affect growth patterns.
   3. Describe selective plant breeding.
   4. Consider how the technologies of cloning and genetic alteration influence the evolution of species.
3. Develop an understanding that technology both shapes society and is shaped by society. (TL)
   1. Explore the relationship between the natural and the constructed worlds.
   2. Investigate how human needs shape the direction and development of technological innovations in modifying plant growth.
   3. Examine how technological innovations produce change in the natural world.

1. Go to a location in your area where the soil is saline. Determine what plant species are growing in the soil. Describe and measure the plants. Talk to some farmers to gather their observations about the effect of saline soils on growth of grain crops, forage crops, and weeds.

   Find a location with a similarly-structured nonsaline soil. Record a description of the species growing there. Compare the observations made at the two locations. Perhaps a regional extension agrologist can suggest some good sites for the observations. Be sure to obtain permission before entering private land. How does saline soil inhibit plant growth?

   Factors: A3, A5, B4, B16, C1, C13, E2, F4

   Objectives: 1.1, 3.2

   Assessment Techniques: short answer test items, presentations, anecdotal records

   Instructional Methods: field trips, interviews, discussion, explicit teaching

2. A recent study stated that seedlings which were touched as they grew developed stockier stems than those which were not touched. Germinate some field peas or lentils in peat pots and divide the pots into three experimental groups. In one group the leaves will be stroked by hand or with popsicle sticks for 30 seconds once an hour during the school day. Another group will be exposed to the breeze of a fan during the school day, and the third will be left alone. Plastic or mulch cover may be needed to prevent drying in the pots on which the fan blows.

   Under what conditions in nature would the seedlings of plants be touched as they grew? How would having stockier stems under these conditions help the plants to survive?

   Factors: A5, B20, C11, C16, E13, F6, G2

   Objectives: 1.5, 3.2

   Assessment Techniques: rating scales, presentations, oral assessment

   Instructional Method: problem solving

3. Design an experiment to test the effects of various strengths of fertilizer solution on the growth of canola seedlings in peat pots.

   Factors: A5, B9, C11, C16, D3, E13, F6

   Objectives: 1.5, 2.2, 3.3

   Assessment Techniques: extended open response test items, performance assessment, rating scales Instructional Methods: conducting experiments, reports

4. How much oxygen do plants produce? How many grass plants would it take to produce enough oxygen per day to supply one person?
5. Why do some plants grow more quickly than others?
6. Why won't some plants grow at all in Saskatchewan? Get a seed catalogue from McFadyen's in Brandon. Determine the hardiness zone in which your school is located. How many plant varieties are listed as hardy for the area of your school. How do hardy plants differ from others?

   Prepare a questionnaire which you can use to structure interviews of gardeners in your area. What experiences have they had with trying to grow plants which were rated as not hardy enough for the area? What suggestions do they have for growing plants to the earliest possible maturity? What other comments can they make about gardening?

7. If using fertilizers helps plants grow, will using more fertilizers help them even more?