approved Adirondack Curriculum Project - www.adkcurriculum.org studenttested
NYS Content Area Standard

MST#1 Student uses scientific inquiry to seek answers and pose questions
MST #2 Student will generate information using appropriate technologies
MST #3 Math – Students will understand mathematical reasoning using data analysis
MST#4 Understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment.
MST #6 Students will understand the relationships and common themes that connect math, science, and technology

NATIONAL STANDARDS
  • Science: Earth & Space Sciences; Life Sciences
  • Life Skills: Thinking & Reasoning; Working with Others
  • Mathematics: Statistics & Data Analysis
 Title: Changing Maple

Grade Level: 7-12, Science

Author: Tammy Morgan and Dan Mayberry, Lake Placid CSD

Email: tmorgan@mail.lakeplacidcsd.net
dmayberry@mail.lakeplacidcsd.net

 Adirondack Curriculum Content Area
_X_ Natural History
___ Human History
___ Culture & the Arts
___ Government & Civics
_X_ Economy
___ Health, Recreation & Life Skills

Investigative Question or Issue: Why do leaves change color in the fall and are changes related to temperature?

Challenge:  
The color of a leaf is related to the concentrations of pigments. In teams, you will conduct a study of leaf pigment concentrations over a 1 month period in the autumn. Review the role of leaf pigments such as chlorophyll a and b, carotenoids, and anthocyanin and what happens when leaves begin to senesce in autumn, then develop some hypotheses about what you expect to happen to the leaf pigment concentrations and their relationship to temperature. Then, once or twice a week, your team will collect data on pigment concentrations. After the data are collected, graphed and analyzed, your group will produce a scientific poster (with all the parts of a scientific paper) to display and present to your classmates and other interested people.

Context for Challenge:
This challenge is intended to help students understand the role of pigments in plant leaves. Student
should connect this understanding with what happens as winter approaches, temperatures get colder,
and leaves turn color and drop. This challenge should also help familiarize students with the scientific
process. Sugar maple (Acer saccharum) is a good species to use, but other species will work. If teams
choose different species then they can compare potential differences.

In preparation for this challenge the teacher should:
1. Find some scientific literature about the colors of leaves, and the physiological roles of each type of pigment.
2. Allot some time for student groups to digest the information together (perhaps with some guiding questions) and to develop at least 2 hypotheses about how pigment concentrations should change over time and in relation to changing temperatures.
3. Discuss the format of the scientific poster they want prepared and have students develop a list of criteria that can be turned into a rubric for assessment of the product.

Procedures:
Leaf Sampling Procedure (for each sampling time/date):
1. Use a hole punch to collect 2 leaf sections from 4 different leaves on one tree. Collect from one leaf in each of the cardinal directions (N,S,E,W).
2. Samples should be gathered on the same days and at the same times

Pigment Extraction and Measuring Procedures:
1. Chlorophyll/carotenoid
  • In a small labeled test tube pipet 3ml of 80% acetone (20% water)
  • Put one of the leaf discs in and use a glass stir rod to gently grind the disc to break up the tissue and allow for better extraction. (repeat with each replicate disc)
    • <>
  • Refrigerate in the dark at approximately 4 C for 24 hours to extract pigment
  • Spin in a centrifuge on high speed for approximately 1.5 minutes
    • <>Pour off the supernatant into a cuvette and read absorption with a spectrophotometer at 470nm for chlorophyll a, 647nm for chlorophyll b, 663nm for carotenoids.
2. Anthocyanin Extraction and Measuring Procedures:
  • In a small labeled test tube pipet 3 mls of (3M HCL:H2O:MeOH) 1:3:16
  • Put one of the leaf discs in and use a glass stir rod to gently grind the disk to break up the tissue and allow for better extraction. (repeat with each replicate disc)
    • <>
  • Refrigerate in the dark at approximately 4 C for 24 hours to extract pigment
  • Spin in a centrifuge on high speed for approximately 1.5 minutes
  • Pour off the supernatant into a cuvette and read absorption with a spectrophotometer at 530 nm
Changing Maple Lab | Pigment Data Collected | Student Work 1 | Student Work 2

Quality Standards:  

  • Produce the project by the due date
  • The poster is creative and informative
  • Information is accurate and addresses the investigative question
  • Includes background information about pigment changes related to time and temperature
  • Meets criteria in the poster assessment rubric (can be student developed or see Product Quality
    Checklist below)
Adapted for the Adirondack Curriculum Project from the work of Education By Design TM and Leading EDGE, LLC ©ACP 2002

   Product Quality Checklist
Date: ________                                                        Class Period: ________
Product Author(s):
Changing Maple
Evaluator Name(s)
 
 Observed Standard/Criteria
Possible
Points
Rating
   Title: Centered, descriptive, large enough, includes authors names
 
  Abstract: Brief description of purpose, methods, results and conclusions (200 to 300 words typically)
 
  Background Information (giving credit to sources – includes:
  • Physiological role of the 3 pigment categories
  • A description of the role of chlorophyll in photosynthesis
  • Reasons for leaf senescence in autumn
  • Possible relationships between pigment concentrations and temperature.
 
  Methods:
  • <>Describes how samples were taken (including number of samples, when taken), how they were prepared & analyzed.
  • Describes how temperature was monitored (how often &
  • Provides enough detail so others could recreate the challenge
  
  

Results:
  • <>2 graphs – one showing how pigments change over time and one showing how temperature changed over time.
  • Graphs must be clearly labeled with units<>
  • <>Each graph must be accompanied by a short paragraph about what trends it shows.
 
  Discussion/Conclusions:
  • <>Describe how different pigments changed over time in relationship to each other and comment on whether or not the data appears to support your hypothesis<><>
  • <><>Describe how temperature changed in relationship to pigment concentrations and comment on whether or not the data appears to support your hypothesis<><>
  • <><>Talk about other research you read that supports or goes against what you saw in your data. Give some possible explanations for this either way.
 

Sections are separated and clearly identified in a neat way


Visuals are helpful and aesthetically pleasing


Poster is easy to read from a 4-6 ft distance





 
TOTALS
 

Comments: nfNorthern Forest Partnership. In addition to the above project. 
Depending on the grade level, this challenge could be used to introduce basic statistical concepts like variation, by teaching how standard deviations are calculated and graphed and what they mean. The experiment can be carried out for as long in the autumn as the teacher has time. It can be done with one species, or several, or each group could look at a different deciduous species. This is a great challenge for
explicitly working with ‘the process of science’.

If time is available, the teacher could involve students in searching for available resources on the topic and the selection of tree species. Student groups could present why they might choose one tree or another and what pigment concentrations they might expect to see in the fall, given what colors they see in each of the species, or the role of that species in the canopy or in a successional sequence. After data for several (3-5) species are collected, groups of students could compare a subset of species and pigment types to answer a question they have phrased and support their discussion of the results using the literature.