Can You Predict How a Bean Plant Will Grow?

Transcription

1 Can You Predict How a Bean Plant Will Grow? In this investigation, you will germinate and grow bean seeds for 2 to 3 days to get them started. Then, you ll turn the bean plant and glass jar on its side in a dark cupboard and leave it for 2-3 more days. Draw a before picture of the plant; be sure to include the stem, leaves and roots. Make some predictions as to what will happen to the stem and the roots, and what they will look like, after several days without sunlight. Discuss and draw your predictions. Why do you feel your prediction will occur? After 2 to 3 days, bring the plants out and carefully observe differences between your before drawing, the prediction drawing and the plant. Review your prediction and observations and write an explanation that fits your observations. Do not be afraid to challenge ideas you began with. 1 of 10

2 Suggested Grade Span 6 8 Task In this investigation, you will germinate and grow bean seeds for 2 to 3 days to get them started. Then, you ll turn the bean plant and glass jar on its side in a dark cupboard and leave it for 2-3 more days. Draw a before picture of the plant; be sure to include the stem, leaves and roots. Make some predictions as to what will happen to the stem and the roots, and what they will look like, after several days without sunlight. Discuss and draw your predictions. Why do you feel your prediction will occur? After 2 to 3 days, bring the plants out and carefully observe differences between your before drawing, the prediction drawing and the plant. Review your prediction and observations and write an explanation that fits your observations. Do not be afraid to challenge ideas you began with. Big Ideas and Unifying Concepts Cause and effect Form and function Life Science Concepts Regulation and behavior Structure and function Mathematics Concepts Data collection, organization and analysis Diagrams Time Required for the Task Two 40-minute class periods. (Periods should be separated by two to three days.) Context Before completing this inquiry, students had learned about plant growth; discussed factors that affect growth, such as sunlight, gravity, nutrients, etc.; and done simple planting investigations. 2 of 10

3 What the Task Accomplishes This task gives students the opportunity to practice using the POE (Predict Observe Explain) method of investigation. Students use their observations to confirm or challenge their preconceptions about phenomena related to plant growth. How the Student Will Investigate To prepare for this investigation, students germinate and grow bean seeds for two to three days in sawdust or paper toweling. Then, they turn the bean plant and glass jar on its side in a dark cupboard. I ask them to draw before pictures of the plant and make some predictions as to what will happen to the stem and roots, and what the plant will look like after two to three days without sunlight. Included with their predictions should be a discussion about why they feel the prediction will occur. Students should also draw their predictions. After two to three days, students bring the plants out and carefully observe differences between their before drawings, the prediction drawings and the actual plants now. (This section can be run as a class discussion so that all agree on the observations. For writing up the explanation, students should review predictions and observations, and write an explanation that fits actual observations/data. (The explanation is best done in small groups or singly, as it is important that individual students confirm, modify or discard their original preconceptions.) Interdisciplinary Links and Extensions Science As an extension activity, students could build mazes inside cardboard boxes (with lids and a light source at some point), watching to see if a plant will grow through the maze to reach the light. Students can try rooting cuttings from snake plants (Sanseveria), planting some right-side up and others upside down. (Root cells will only grow down from the right-side up cuttings.) Teaching Tips and Guiding Questions I use a teaching model called POE (Predict, Observe, Explain), which is extremely useful in having students uncover and share their preconceptions through predicting the outcome of a short and simple experiment. Through observation of the outcome, the students (with the aid of the teacher as facilitator) focus on the important variables and relationships, not on the materials and procedure, which can often distract them. Finally, through their explanations, students construct personal meaning, as their preconceptions will be confirmed, modified or occasionally thrown out, and a new concept of what is happening will be formed. 3 of 10

4 Some guiding questions are: Before: After: Why do some plants grow up? Why do roots grow down? How do the plants know up from down? Why shouldn t you plant seeds too deep? (The rule of thumb is to plant seeds no deeper than their size. They only have enough stored food to germinate and grow to the surface before they need sunlight. Planted too deep, they will not make it to the surface before they use up stored nutrients.) Do we set seeds up and down when we plant our gardens? How do you know which way is up? (Hint: if you are not sure, plant it on its side so it will have a better chance. What role does gravity play in plant growth? How would plants grow in a space station? Why do you think that? 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: Students observe that specialized cells perform specialized functions (root cells grow roots and stem cells grow stems). Life Science Regulation and Behavior: Students understand and can explain that all organisms must maintain a stable internal environment to survive, by sensing unbalance and changing physiological activities as they relate to sunlight, gravity, etc. Scientific Method: Students observe and explain reactions when variables are controlled (cause and effect). Mathematics: Students use diagrams and collect, organize and analyze data appropriately. 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: Observing, predicting/hypothesizing, collecting and recording data, manipulating tools, drawing conclusions, communicating findings, challenging misconceptions and raising new questions. 4 of 10

5 Other Science Standards and Concepts Addressed Scientific Theory: Students look for evidence that explains why things happen and modify explanations when new observations are made. Suggested Materials Paper towels or sawdust Glass jars Bean seeds Water Closet or cupboard to keep plants in for several days Possible Solutions Students need to have a before picture of the plant stem and leaves and roots; a prediction, including a reason for it; and a drawing of the prediction. Observations should be recorded and used in the explanation to evaluate the prediction. Students should observe that during the time in the darkness, the plants responded to gravity roots grew down and stems grew up. Task-Specific Assessment Notes Novice This student s explanation is incomplete, lacking a change in or confirmation of the original prediction. The student s prediction does not include a reason for why s/he is making the prediction. Observations are correct but are not used to clarify scientific reasoning about why the plant grows up. The student shows little evidence of conceptual understanding. Apprentice This student bases the explanation on the observed characteristics of the plant but does not grasped the cause-effect relationship of gravity and plant growth (direction of growth). The student predicts reasons that gravity will pull the plant stem down, but the student does not return to discuss gravity in his/her explanation or to mention the lack of light. There is little evidence of conceptual understanding. Practitioner This student grasps the cause-effect relationship of gravity and the directional growth of the plant. The student includes all required drawings. The student predicts that gravity will pull the plant roots and stem down. In the explanation, accurate observations are used to discuss how the roots and stem sense up and/or gravity and grow in different directions evidence of conceptual understanding. 5 of 10

6 Expert All required drawings are included. The prediction includes several possible reasons for what might happen. Observations are detailed and include the fact that the plant has turned yellow at the top. The student s explanation is complete and detailed. The explanation specifically focuses on the cause-effect relationship of gravity and the directional plant growth of the stem and roots. It also includes a comment about the lack of light having an effect on the color. 6 of 10

7 Novice 7 of 10

8 Apprentice 8 of 10

9 Practitioner 9 of 10

10 Expert 10 of 10