Planting Seeds, Part 1: Can You Design a Fair Test?

Transcription

1 Planting Seeds, Part 1: Can You Design a Fair Test? In this investigation, your team will choose 2 or 3 seeds in order to design an investigation to learn something more about them. First, you will need to think about something you would like to find out and how you might test it. Make a list of what you will use and what you will need to measure. Make a prediction about what you think will happen, and tell how you will be sure that it is a fair test. You will use your observation data to tell your results and make some conclusions about what you have learned. 1 of 12

2 Suggested Grade Span 3 5 Task In this investigation, your team will choose 2 or 3 seeds in order to design an investigation to learn something more about them. First, you will need to think about something you would like to find out and how you might test it. Make a list of what you will use and what you will need to measure. Make a prediction about what you think will happen, and tell how you will be sure that it is a fair test. You will use your observation data to tell your results and make some conclusions about what you have learned. Big Ideas and Unifying Concepts Cause and effect Change and constancy Form and function Interdependence Systems Life Science Concepts Evolution, diversity and adaptations Populations and ecosystems Regulation and behavior Reproduction and heredity Structure and function Mathematics Concept Data collection, organization and analysis Time Required for the Task Approximately two to three classes for Part 1 (planning and planting) and five to ten days for Part 2 (collecting data and reporting results). 2 of 12

3 Context This investigation was done last spring as part of a unit of study about plants. To introduce the concepts of fair tests and testable questions, students were given the opportunity to explore how selected seeds grew under certain conditions. First, as a class we brainstormed many questions that we could test, such as: Which seed will grow the tallest? Which seed will sprout the fastest? Then, I modeled collecting data using a recording sheet, Investigation Planner, from Science Alive: A World of Matter classroom materials, and we completed one sample together. When student teams began to plan their investigations, they had some understanding of the topic as well as a basic idea of the skills of scientific investigation. What the Task Accomplishes This task provides information to the teacher about whether students have a clear understanding of how to apply the scientific method (controlling variables and collecting, recording and interpreting data) when designing their own investigation. In Part 1, the focus is on planning the investigation as a fair test. Assessment at this point in the investigation assists the teacher in being able to ensure that students will modify their designs, if needed, before collecting their data. How the Student Will Investigate The first half of the recording sheet, Investigation Planner, is used to guide students through this part of the investigation. Once teams select a testable question, they make a prediction and plan what materials they will use. Before conducting their tests, their plan is reviewed and modifications or clarifications can be made. Students then plant seeds and record observations in drawings and words to share with the class. Because students work in teams, fewer materials and less space are necessary for individual projects. Cooperative groups have assigned roles (materials manager, information recorder, overseer/timekeeper) to complete the planning and planting. Pots are placed on plastic trays in the GrowLab for observation. Each student makes individual observations in a journal, but the team collaborates to produce the final report. New roles can be assigned for Part 2 by having an artist and recorder complete each day s observations for the team and having others check for accuracy and completeness. Interdisciplinary Links and Extensions Science Students can test the germination rates found on the seed packets or compare year-old seeds to current-year s seeds. If planted in groups of 10 seeds, percentages are also easy to compute (i.e., 6 of 10 seeds germinated in three days = 60%). Students can test how different soils affect 3 of 12

4 the rates of growth of plants and the germination success of seeds. Students can test the effects of different planting depths on the same seeds and determine optimum depths. (If planted too deep, most seeds will not be able to make it to the surface of the soil; too close to the surface, roots may not take hold well, seeds are likely to be eaten by birds, etc.) Art/Writing Students can design seed packets for new hybrids or to describe themselves! These make colorful classroom posters. Mathematics Students can plan backwards for a garden, planting seeds at different times to have a harvest at the same time. (For example, they could map out dates to plant each type of seed for a bouquet of cut flowers or ingredients of a tossed salad.) Students can dissect a plant (such as a marigold or seedpod) to determine how many seeds one flower and one plant might produce. Teaching Tips and Guiding Questions Life science topics that involve planting seeds, transplanting and propagating plants, and observing plant growth under different conditions are great activities for the spring months. Students are learning concepts related to plants as well as becoming more familiar with applying the scientific investigation process and designing fair tests. Guiding questions to ask students at the beginning of this investigation might include: What is your testable question? What are your ideas about your question? What have you learned or observed so far that will help you make a prediction or hypothesis? How will you test your question? What are some possible variables to test? (length of germination, rate of growth, effects of different planting depths for the same seeds, etc.) What would happen if you...? How will you control variables? (same number of seeds; same amounts of water, light, soil; same container size; etc.) What variable will you test? How will you make this a fair test? What materials will you need? What will you measure? What tools do you need? How will you record your data? How often will you make your observations? Did you mark each seed type in its pot? Have you learned anything that surprised you so far? 4 of 12

5 Concepts to be Assessed (Unifying concepts/big ideas and science concepts to be assessed using the Science Exemplars Rubric under the criterion: Science Concepts and Related Content) Life Science Structure and Function; Reproduction and Heredity: Students identify characteristics of organisms each plant has different structures that serve different functions in growth, survival and reproduction. Students understand the characteristics of seeds by describing some of their needs, aspects of their immediate environments, some of their structures (seed coat, root hairs, etc.), and the effects of weather or other events. Life Science Regulation and Behavior: Students understand that all organisms must be able to obtain and use resources, grow, reproduce and maintain stable internal conditions while living in a changing environment. Life Science Evolution, Diversity and Adaptations: Students understand that species acquire many of their unique characteristics including, structures, behaviors or physiology, through biological adaptation that enhances survival and reproductive success. Life Science Populations and Ecosystems: Students identify some patterns of similarities and differences among plants and recognize their interdependence with other living things (systems and interdependence). Scientific Method: Students observe and explain reactions with some justification, using data and prior knowledge, when variables are controlled (cause and effect). Students determine the patterns and/or which kinds of change are happening by making observations and measurements over time (change and constancy). Mathematics: Students collect, organize and analyze data. Skills to be Developed (Science process skills to be assessed using the Science Exemplars Rubric under the criteria: Scientific Procedures and Reasoning Strategies, and Scientific Communication Using Data) Scientific Method: Raising testable questions, predicting/hypothesizing, observing, collecting/recording data, interpreting data and drawing conclusions. Other Science Standards and Concepts Addressed Scientific Method: Students hypothesize, observe, predict, investigate and explain phenomena. Students control variables. 5 of 12

6 Scientific Theory: Students use evidence to construct an explanation based upon their observation and the concepts that have been learned. Students modify explanations when new observations are made. Life Science Structure and Function: Students understand the characteristics of organisms (needs, environments, structures and behaviors), see patterns of similarity and differences among living organisms, and recognize the interdependence of all systems that support life. Life Science Evolution, Diversity and Adaptations: Students understand that organisms can survive only in environments that meet their needs, and that organisms have distinct structures that have developed to help them to function and survive. Life Science Structure and Function; Reproduction and Heredity: Students observe that each plant has different structures that serve different functions in growth, survival and reproduction. Suggested Materials Essential items to have available during these investigations include potting soil, cups or pots (or even washed out milk cartons), water and a variety of seeds with short germination times (under two weeks!). Many of our seeds had been donated by parents and the Parent-Teacher Group. It is important for students to label their pots with what was planted so that they do not get mixed up during the observation weeks. Grow lights or a GrowLab were not essential, since this was primarily a seed germination activity. However, for extended investigations with plants, I would suggest having plants under lights. I also have measuring tools, such as rulers, eyedroppers and measuring cups, for students to use. Possible Solutions For each investigation, students generated their questions; therefore there are a variety of possible designs. What is most important in this investigation is that students demonstrate an understanding of how to control variables, record their data and accurately interpret the data. Each part of the planning form should be completed: (1) what we want to find out, (2) our idea for an experiment, (3) materials needed, (4) what we will measure, (5) our predictions, and (6) how we will make it a fair test. For the last two questions on the planning form (What actually happened? and What I found out), I assessed to see if students collected data and stated results related to their original question. Task-Specific Assessment Notes Novice These students state a question to answer, but the investigation does not seek to test a variable or compare different results. Materials are listed and there is some evidence of controlling 6 of 12

7 variables; however, only the amount of soil is the variable we are sure about. The interpretation of data shows little conceptual understanding about plants, since the students state that the flower became a weed. Apprentice These students did complete the task, asking a testable question regarding the effects of different locations on plant growth; however, the actual investigation does not appear to follow through with the original plan. There is evidence of understanding what variables to control. Practitioner These students include a testable question and show evidence of understanding fair testing and controlling variables. (Both plants are in the GrowLab and get 1/2 cup of water each day.) The procedures followed and the results based on data collected match what was planned to be tested and measured. It is not clear how the plant is measured for growth, unless it is simply by making an observation. Expert These students include a testable question and provide clear and detailed descriptions of the procedures they followed. They note several ways variables are controlled using precise measurements (four squirts of water each day, each seed planted one inch deep). Thinking is extended when the students make comparisons with other plants in the room and dig up their seeds to further observe what is happening. They consider modifying the investigation (changing amounts of water being used) based on their observations. 7 of 12

8 Novice 8 of 12

9 Apprentice 9 of 12

10 Practitioner 10 of 12

11 Expert 11 of 12

12 Expert 12 of 12