Lesson Outlines
Lesson 1
Introduction to the Maple Syrup Industry
Lesson 2
Tree Anatomy
Lesson 3
Sap Movement Physiology
Lesson 4
Tree Identification
Lesson 5
Tapping and Collecting
Lesson 6
Boiling and Filtering Syrup
Lesson 7
Cleaning and Sanitizing Equipment
Lesson 8
The Experiment
Data Sheets / Questions
Note Taking Guides
Note Taking Guide Keys
Worksheets / Quizzes
Fast Write Instructions
Materials and Resource List
Bibliography
Maple Syrup in the Classroom
Learning Benchmarks –
Transportation of nutrients in xylem and phloem
Tree anatomy
Maple Syrup Production guidelines
Tree Identification
Measurement
Experimentation of tree species and observable characteristics on sap yield and sap sugar
concentration
Maple Syrup Production Methods
Materials –
One or more Turkey Cooker(s) Borrowed 75.00
Plastic Spiles .37 each x 15 = 5.55
Five Gallon Buckets free from local restaurants and school cafeteria
Plastic Tubing 1 roll 24.50
Sap and Syrup Hydrometer 12.00, 10.50 and 20.00
Thermometer Should be included with Turkey Cooker 5.00
Drill Bits Borrow if not already at hand Leader bit 15.00
Cordless Drill Borrow if not already on hand 100.00
Syrup Containers Pint Containers - .81 each x 15 = 12.15
Approximately 10 – 15 maple family trees.
Paper and Felt Filter 5.00, 10.00
Extra Pan to Filter into 40.00
Resource Books –
North American Maple Syrup Producers Manual 10.00
Backyard Sugarin’ 9.50
Filter
All sugaring supplies available at:
Sugar Bush Supplies Co.
2611 Okemos, Rd.
Mason, MI 48854
517-349-5185
Online
http://maple.dnr.cornell.edu
www.barnsbarnsbarns.com/ noff/sugarmaple.html
Each lesson includes the following.
 Outline for Teacher
 PowerPoint
 Note Taking Guide
 Worksheet / Quiz
Lesson 1 – Introduction to Maple Syrup Industry
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Make overheads from master if using a projector.
Interest Approach
Have students spend 5 – 10 minutes writing what they know about maple syrup production. This
could be in a journal or as a fast write assignment.
Allow an additional 5 minutes to share as a group.
Content of PowerPoint (Handout Note Taking Guide in Advance)
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Historical Importance
Economic Impact
Discovery of Maple Syrup
Geography of where maple syrup is produced
The Basic Process
Evaluation
Students complete worksheet / quiz with or without note taking guide.
Lesson 2 – Tree Anatomy
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Print overheads from master if using a projector.
Interest Approach
Have students spend 5 – 10 minutes writing “What they know about different parts of a tree and
what the tree parts do.” This could be in a journal or as a fast write assignment.
Allow an additional 5 minutes to share as a group.
Continue by asking the question, “What characteristics of a tree are important for maple syrup
production.”
Allow students to predict what kind of tree is the best for maple syrup production.
Content of PowerPoint (Handout Note Taking Guide in Advance)
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Crown
Leaves
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Functions
Photosynthesis
Cross Section
Parts of Leaves
Types of Leaves
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Functions
Parts – Cross Section
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Functions
Types of Roots
Trunk
Roots
Evaluation
Students complete worksheet / quiz with or without note taking guide.
Lesson 3 – Sap Movement Physiology
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Make overheads from master if using a projector.
Interest Approach
Have students spend 5 – 10 minutes in a brainstorming session on what characteristics will
impact sap flow and sap sugar concentration.
Allow an additional 5 minutes to share as a group.
Content of PowerPoint (Handout Note Taking Guide in Advance)
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Factors Effecting Sap Movement
Explanation of How Factors Effect Movement
Evaluation
Students draw diagram of a tapped tree at temperatures above and below freezing showing the
direction the sap / water is moving and whether pressure in the tree is positive or negative.
Students should be able to predict when they will need to collect and boil sap throughout the
season.
Lesson 4 - Tree Identification
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Make overheads from master if using a projector.
Interest Approach
Have students spend 5 – 10 minutes writing about “How we can tell the difference between trees,
especially similar trees. This could be in a journal or as a fast write assignment.
Allow an additional 5 minutes to share as a group.
Content of PowerPoint (Handout Note Taking Guide in Advance)
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Basic Identifying Characteristics
Budding Patterns
 Opposite
 Alternate
Tree Characteristics for:
 American Beech
 Sugar Maple
 Red Maple
 Silver Maple
 Norway Maple
Evaluation
Students draw twigs of all species except Norway Maple paying special attention to the budding
pattern, shape of buds and number of buds.
Have students work in pairs on a nature walk and see if they can find maple or beech trees and
identify them.
Lesson 5 – Tapping and Collection
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Make overheads from master if using a projector.
Interest Approach
Have students spend 5 – 10 minutes writing what they know about maple syrup production. This
could be in a journal or as a fast write assignment.
Allow an additional 5 minutes to share as a group.
Content of PowerPoint (Handout Note Taking Guide in Advance)
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Guidelines for # of Taps per Tree
Measuring Tree Diameter
 Diameter Tape
 Biltmore Stick
 String
Selecting the Best Trees
Tapping Procedure
Setting the Spile
Collection Techniques
Storage of Sap
Evaluation
Have students cut and color a string according to the instructions in the PowerPoint.
Students complete worksheet / quiz with or without note taking guide.
Assists students in selecting and tapping trees.
Lesson 6 – Boiling and Filtering Syrup
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Make overheads from master if using a projector.
Interest Approach
Have students complete a “taste test” between commercial syrups (Mrs. Butterworth’s) and
100% pure Maple Syrup.
Have the students compare the ingredients and food label.
Content of PowerPoint (Handout Note Taking Guide in Advance)
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Rule of 86
Basic Syrup Production Methods and Principles
Evolution of Syrup Making Equipment
Testing Finished Syrup
Using a Hydrometer
Filtering Syrup
Canning
Evaluation
Students complete worksheet / quiz with or without note taking guide.
Assist students in making maple syrup.
Lesson 7 – Cleaning and Sanitizing Equipment
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Make overheads from master if using a projector.
Interest Approach
Explain to students that there are three parts to every job; getting out, doing and putting away. It
is important to properly clean and sanitize equipment in a food production system. Time spent at
the end of the season will save time in the future.
Content of PowerPoint (Handout Note Taking Guide in Advance)
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Importance of Cleaning
Cleaning Directions
Evaluation
Student clean pails, spiles and other equipment as instructed in PowerPoint.
Lesson 8 – The Experiment
Lesson Outline
Advanced Preparation
1. Prepare copies of note taking guide.
2. Set up computer and projector or overhead projector.
3. Make overheads from master if using a projector.
Interest Approach
Have students spend 5 – 10 minutes writing what they know about maple syrup production. This
could be in a journal or as a fast write assignment.
Allow an additional 5 minutes to share as a group.
Content of PowerPoint (Handout Note Taking Guide in Advance)
Experiment Process
Students form prediction
Teacher explains the use of each of the materials
Students are broken into groups and design experiment
Groups present experiment designs.
Class discussion about the advantages and disadvantages ends with a vote on final
experiment design.
Sample Experiment is provided for teacher.
Data collection
Data Collection from Trees Volume of Sap and Sugar Concentration.
Evaluation will be based on Lab Report and Written Exam.
Students will prepare to teach lesson to third graders as part of the chapter’s Food for America
program.
Syrup can be used for classroom pancake day; samples for third graders; teacher appreciation
breakfast during National FFA Week; or pancake breakfast fundraiser.
10-15 trees should produce 4-5 gallons of syrup depending on size of the tree. 1 qt per tap.
Maple Sap Collection Daily Data Sheet
Date: _____________
Taphole I.D.
Volume of Sap Collected
% Sugar Concentration
Date – Date of Collection.
Taphole I.D. – each taphole should be identified.
Volume Sap Collected – Measured in Quarts.
% Sugar Concentraion – Measured in Brix with a sap hydrometer.
Quality of Sap – Clear, Cloudy or Yellow.
Quality of Sap
Maple Sap Collection Daily Data Sheet
Sample
Date: ___3/15/05___
Taphole I.D.
Volume of Sap Collected
% Sugar Concentration
Quality of Sap
1
2
3
4
5
13
7
12
9
2
2.0
1.5
1.0
3.0
1.8
Clear
Clear
Clear
Cloudy
Yellow
Date – Date of Collection.
Taphole I.D. – each taphole should be identified.
Volume Sap Collected – Measured in Quarts.
% Sugar Concentraion – Measured in Brix with a sap hydrometer.
Quality of Sap – Clear, Cloudy or Yellow.
Maple Sap Collection Master Data Sheet
Name: ____________________
Taphole
I.D.
Tree
Species
Tree
Diameter
Crown
Circumference
Tree
Location
# of Taps
on Tree
Total Volume
of Sap
Collected
Taphole I.D. – each taphole should be identified.
Tree Species – Red Maple, Sugar Maple, American Beech or Silver Maple.
Tree Diameter – Measured in inches.
Crown Circumference – Measured in feet around the drip line of the tree.
Tree Location – Woodlot or Open Space.
# of Taps on Tree – 1 or 2
Total Volume Sap Collected – Measured in Quarts.
Average % Sugar Concentraion – Measured in Brix with a sap hydrometer.
Average
% Sugar
Concentration
Maple Sap Collection Master Data Sheet
Sample
Taphole
I.D.
Tree
Species
1
2
3
4
5
Tree
Diameter
Sugar
Red
Silver
Beech
Red
Crown
Circumference
13
21
15
14
15
Tree
Location
46
57
33
29
75
# of Taps
on Tree
Woodlot
Woodlot
Woodlot
Woodlot
Open
Total Volume
of Sap
Collected
1
2
1
1
1
Taphole I.D. – each taphole should be identified.
Tree Species – Red Maple, Sugar Maple, American Beech or Silver Maple.
Tree Diameter – Measured in inches.
Crown Circumference – Measured in feet around the drip line of the tree.
Tree Location – Woodlot or Open Space.
# of Taps on Tree – 1 or 2
Total Volume Sap Collected – Measured in Quarts.
Average % Sugar Concentraion – Measured in Brix with a sap hydrometer.
Average
% Sugar
Concentration
44
37
60
53
26
2.9
2.0
1.6
2.2
1.8
Lesson Eight
Final Questions
Directions: Use the data from your observations and background knowledge to
answer the following questions.
1. Which tree species would you choose to tap in your own sugar bush? Why?
2. What effect does tree species have on the % sugar concentration of the sap?
3. What effect does tree species have on the total volume of sap?
4. What effect does tree diameter have on % sugar concentration of the sap?
5. What effect does tree diameter have on the total volume of sap?
6. What effect does the size of tree canopy have on % sugar concentration of the
sap?
7. What effect does the size of tree canopy have on the total volume of sap?
8. What effect does the tree location have on the size of the canopy?
9. What effect does tree location have on the % sugar concentration of the sap?
10. What effect does tree location have on the total volume of sap?
11. What effect does tree species have on the size of the canopy?
12. What is the relationship between tree species and tree diameter?
13. What is the relationship between tree diameter and size of the canopy?
14. What effect does tree species have on sap quality?
Name ________________
Date _________________
Lesson 1
Worksheet / Quiz
Introduction to Maple Syrup Industry
1. How many dollars does the maple syrup industry contribute to the U.S.
economy?
2. Who first discovered maple syrup?
3. Where does Michigan rank in the production of maple syrup?
4. Where is maple syrup commercially produced?
5. What is the leading state of production?
6. When is maple syrup made?
7. What temperature conditions are needed to make maple syrup?
8. What is the first step in producing maple syrup?
Name ____KEY________
Date _________________
Lesson 1
Worksheet / Quiz
Introduction to Maple Syrup Industry
1. How many dollars does the maple syrup industry contribute to the U.S.
economy?
$50 million
2. Who first discovered maple syrup?
Native Americans
3. Where does Michigan rank in the production of maple syrup?
5th
4. Where is maple syrup commercially produced?
Northeast US and Southeast Canada
5. What is the leading state of production?
Vermont
6. When is maple syrup made?
February, March, and April
7. What temperature conditions are needed to make maple syrup?
Freezing nights and warm days
8. What is the first step in producing maple syrup?
Selecting Trees to Tap
Name ________________
Date _________________
Lesson 2
Worksheet / Quiz
Tree Anatomy
1. What are the three main parts of a tree?
2. What part of the tree consists of the branches and leaves?
3. Where does photosynthesis take place?
4. What is the basic reaction for photosynthesis?
5. What part of the leaf is responsible for photosynthesis?
6. What is the main body of the leaf called?
7. What is the tip of the leaf called?
8. What is the outside edge of a leaf?
9. What are the three types of leaves?
10.What are two functions of the trunk?
11.What are the tissues called that transport water and nutrients up and down
the trunk?
12.What are three functions of the roots?
13.What are the two types of roots?
14.Where is the sapwood found in a tree trunk?
15.What is an example of a plant with a taproot?
Name ______KEY______
Date _________________
Lesson 2
Worksheet / Quiz
Tree Anatomy
1. What are the three main parts of a tree?
Roots, Trunk and Crown
2. What part of the tree consists of the branches and leaves?
Crown
3. Where does photosynthesis take place?
Leaves
4. What is the basic reaction for photosynthesis?
Carbon dioxide + Water = Glucose and Oxygen
5. What part of the leaf is responsible for photosynthesis?
Chloroplasts
6. What is the main body of the leaf called?
Blade
7. What is the tip of the leaf called?
Apex
8. What is the outside edge of a leaf?
Margin
9. What are the three types of leaves?
Simple, Compound and Needle
10.What are two functions of the trunk?
Transport water and nutrients, Support leaves, Store food, Diametrical
growth
11.What are the tissues called that transport water and nutrients up and down
the trunk?
Xylem and Phloem
12.What are three functions of the roots?
Absorb water and nutrients, Transport water and nutrients, Anchor plant,
Store Food
13.What are the two types of roots?
Fibrous and Tap
14.Where is the sapwood found in a tree trunk?
Between the Xlyem and Heartwood
15.What is an example of a plant with a taproot?
Carrot
Name ________________
Date _________________
Lesson 5
Worksheet / Quiz
Tapping and Collecting
1. What must be measured to determine the number of taps that can be put
into a tree?
2. What are three ways to measure tree diameter?
3. How many taps should be put into a tree with a 16 inch diameter?
4. Where is tree diameter measured?
5. What is the smallest tree that is recommended to be tapped?
6. How deep should the hole be drilled into the tree?
7. What should be checked to see if the tree is healthy enough to be tapped?
8. What angle should the tree be drilled?
9. Where should sap be stored?
10.What should sap look like?
11.How many gallons of sap would be required to make one gallon of syrup
if it was 1.5% sugar?
12.How many gallons of 2.5% sugar sap are needed to make one gallon of
syrup?
13.When should sap be filtered?
14.What size drill bits are commonly used to tap trees?
15.How many taps should be put in a 21 inch diameter tree?
Name _____KEY_______
Date _________________
Lesson 5
Worksheet / Quiz
Tapping and Collecting
1. What must be measured to determine the number of taps that can be put
into a tree?
Diameter
2. What are three ways to measure tree diameter?
Biltmore Stick, Diameter Tape, String
3. How many taps should be put into a tree with a 16 inch diameter?
One
4. Where is tree diameter measured?
4.5 feet from the base
5. What is the smallest tree that is recommended to be tapped?
12 inches
6. How deep should the hole be drilled into the tree?
2 inches
7. What should be checked to see if the tree is healthy enough to be tapped?
Crown for dieback, Trunk for hollow, Base for physical damage
8. What angle should the tree be drilled?
10 degree upward
9. Where should sap be stored?
Cool location
10.What should sap look like?
Clear like water
11.How many gallons of sap would be required to make one gallon of syrup
if it was 1.5% sugar?
57.33
12.How many gallons of 2.5% sugar sap are needed to make one gallon of
syrup?
34.4
13.When should sap be filtered?
Before it is put into a storage tank
14.What size drill bits are commonly used to tap trees?
5/16” and 7/16”
15.How many taps should be put in a 21 inch diameter tree?
Two
Name ________________
Date _________________
Lesson 6
Worksheet / Quiz
Boiling and Filtering Syrup
1. What should be done if scum develops on the surface of the boiling sap?
2. How is sap converted into syrup?
3. If boiling sap starts to foam or boil over what should be done?
4. Approximately how many gallons of water will have to be boiled of to
make a half gallon of syrup?
5. If there only one “right” way to make syrup?
6. At what temperature is syrup “finished”?
7. What is the most accurate method of testing syrup?
8. What is removed when the syrup is filtered?
9. What temperature should syrup be canned?
10.Should syrup be filtered hot or cold?
11.What must be done after the container is filled and the lid is secured?
Why?
12.List the advancements of methods used to make maple syrup starting
with a single kettle.
Name ______KEY______
Date _________________
Lesson 6
Worksheet / Quiz
Boiling and Filtering Syrup
1. What should be done if scum develops on the surface of the boiling sap?
Skim off with wire strainer
2. How is sap converted into syrup?
Boiled to remove water
3. If boiling sap starts to foam or boil over what should be done?
Add a drop of oil or butter
4. Approximately how many gallons of water will have to be boiled of to
make a half gallon of syrup?
20
5. If there only one “right” way to make syrup?
No, no two sugar houses are the same
6. At what temperature is syrup “finished”?
219 degree Fahrenheit or 7 degree above the boiling of water
7. What is the most accurate method of testing syrup?
Hydrometer
8. What is removed when the syrup is filtered?
Sugar sand, calcium and magnesium precipitates
9. What temperature should syrup be canned?
180 degrees Fahrenheit
10.Should syrup be filtered hot or cold?
Hot, it moves through the filters faster
11.What must be done after the container is filled and the lid is secured?
Why?
Can must be placed on its side or upside down to sterilize and seal the
container
12. List the advancements of methods used to make maple syrup starting
with a single kettle.
Multiple Kettles, Flat Bottom Pan, Arch or Enclosed Fire Box, Flue Pan
angiosperm:
flowering plant bearing seeds enclosed in a fruit
annual:
a plant that lives only one year
bark:
a general term for all tissue outside the cambium; parts are inner and outer
bark
cambium:
the thin layer of dividing cells located between the phloem and xylem of a
tree; it produces new phloem cells toward the outside of the tree ( inner bark) and new xylem cells
toward the inside (sapwood) and is responsible for growth in diameter.
crown:
the leafy canopy of a tree including the branches
perennial:
lives more than one year
diameter:
distance across a circle at the center
deciduous:
drops all its leaves at one time (fall)
evergreen:
drops its leaves gradually; never leafless
gymnosperm:
a plant bearing its seeds exposed, as in a cone
hardwood:
a broad-leaved tree
perennial:
a plant that lives more than one year
phloem:
the food-conducting tissues of a plant; located outside the cambium and
beneath the outer bark of a tree
root:
the below-ground plant which anchors and absorbs water and minerals
softwood:
a needle-leaf tree; a conifer
trunk:
the above-ground, woody stem of a tree
xylem:
the water- and mineral-conducting tissue of a plant; located inside the
cambium
Using a hydrometer to measure
the sugar concentration of sap and syrup
Background
Consider a rock and a piece of styrofoam, both the same size. If you put them in a
bucket of water, which one sinks? As you know, the styrofoam will float, and the rock
will sink. This is because the rock is denser than water, while the styrofoam is less
dense than water.
An object's density is a measure of how much it weighs compared to how much space it
fills. In the example above, both objects are exactly the same size, but the rock is much
heavier. Therefore, the rock is denser than the styrofoam. As with solids like rocks and
styrofoam, different solutions (liquids) can have varying densities, too.
Have you had the chance to go swimming in a lake and the ocean? If so, you may have
noticed that it was easier to float in the ocean. Because the ocean contains more salt
than most freshwater lakes, ocean water is denser than lake water. Objects float higher
- or displace less liquid - in solutions with greater density.
A hydrometer uses this principle - density - to measure how much sugar is in sap. If you
take a sample of sap from two different trees, the sap containing more sugar will be
denser than the sap containing less sugar. A hydrometer measures how dense sap is
by recording how much water is displaced when it floats in the sap.
The hydrometer will displace less water (will float higher) in sap that contains more
sugar than it will in sap that contains less sugar. Hydrometers use this information to
record the sugar concentration of maple sap.
Using a hydrometer
Because producers want to measure the sugar content of sap (1-6% sugar), syrup (6667%), and concentrated sap (between 6 and 66%), hydrometers are available with
several different scales. Some hydrometers can measure the low concentrations of
sugar present in fresh sap, while others measure the higher concentrations found in
syrup.
Once you have obtained a hydrometer, you may be interested in measuring the sugar
content of sap from maple trees in your yard or schoolyard, or you may want to
measure the sugar content of maple syrup you have purchased or made yourself. You
may even be interested in participating in the Cornell Sugar Maple Tree Improvement
Program.
To measure sap sugar content, you will need a hydrometer, and hydrometer cup, and a
thermometer. Place the hydrometer cup in a flat pan (the pan will collect any sap that
overflows). Completely fill the hydrometer cup with sap or syrup.
Immerse the hydrometer carefully, making sure it doesn't bounce off the bottom, and
wait a few seconds until it stops moving. Carefully, making sure your eyes are level with
the top of the cup, read the marking on the hydrometer that corresponds with the top of
the syrup or sap. Take your readings from the bottom of the meniscus (see Figure 1).
The meniscus is the thin film of liquid that adheres to the sides of the hydrometer and is
above the true level of the liquid.
Figure 1.
Take the temperature of the sap or syrup inside the
hydrometer cup. To be very accurate, you will need
to adjust the hydrometer (Brix) reading depending
on the temperature. We have provided a table
below that contains adjustment information for very
concentrated sap and maple syrup (sugar
concentration, or Brix, greater than 60.0). If you are
interested in accurately determining the sugar
content of fresh sap, you will need to do some
research to find a similar table.
For maple syrup, use the chart in Table 1 to adjust the reading that you measured with
the hydrometer. The "brix" reading from the table is the sugar concentration of the sap
or syrup.
Table 1. Brix adjustment scale
Temperature of syrup
in hydrometer cup (F)
Correction to be subtracted from (-) or added to (+)
observed Brix reading
60.0 - 69.9 Brix
45
50
55
60
65
68
70
75
80
85
90
95
-1.0
-0.8
-0.5
-0.1
-0.1
0
+0.1
+0.3
+0.5
+0.8
+1.0
+1.2
69.9 Brix and higher
-1.0
-0.8
-0.6
-0.1
-0.1
0
+0.1
+0.3
+0.5
+0.8
+1.0
+1.2
Sap Flow
One of the great mysteries of maple syrup is what causes the sap to flow out of the
trees. Following is an explanation of how temperature fluctuations and pressure and
suction in the tree cause sap to flow.
Early in the spring, when the maple trees are still dormant, temperatures rise above
freezing during the day but drop back below freezing at night. This fluctuation in air
temperature is vital to the flow of sap in sugar maple trees.
What causes the sap of maple trees to flow in the spring? During warm periods when
temperatures rise above freezing, pressure (also called positive pressure) develops in
the tree. This pressure causes the sap to flow out of the tree through a wound or tap
hole. During cooler periods when temperatures fall below freezing, suction (also called
negative pressure) develops, drawing water into the tree through the roots. This
replenishes the sap in the tree, allowing it to flow again during the next warm period.
Although sap generally flows during the day when temperatures are warm, it has been
known to flow at night if temperatures remain above freezing.
Thus, pressure and suction are essential to sap flow. But how do the pressure and
suction develop?
Sap flows through a portion of the outer tree trunk called sapwood. Sapwood consists of
actively growing cells that conduct water and nutrients (sap) from the roots to the
branches of the tree. During the day, activity in the cells of sapwood produces carbon
dioxide. This carbon dioxide is released to the intercellular spaces in the sapwood. In
addition, carbon dioxide in sap is released into the spaces between the cells. Both of
these sources of carbon dioxide cause pressure to build up in the cells. A third source of
pressure is called osmotic pressure, which is caused by the presence of sugar and
other substances dissolved in the sap. When the tree is wounded, as when it is tapped
by a maple producer, the pressure forces the sap out of the tree.
At night or during other times when temperatures go below freezing, the carbon dioxide
cools and therefore contracts. Some of the carbon dioxide also becomes dissolved in
the cooled sap. Finally, some of the sap freezes. All three of these factors create
suction in the tree. This causes water from the soil to be drawn up into the roots and
travel up through the sapwood. When temperatures rise above freezing the next day,
sap flow begins again.
Thus, the cycle of warm and cool periods is essential for sap flow. Temperatures too
warm or too cool during the short, six-week "sap season" will reduce the amount of sap
flow. This will result in lower maple syrup production or a "bad year" for maple
producers in the region.
The sap in sugar maple contains a high concentration of sugar compared to the sap of
other trees. The sugar in maple sap is the product of photosynthesis that occurred
during the previous summer. Carbohydrates produced by photosynthesis are stored in
the tree in the form of starch. Starch is converted to sucrose (sugar) and dissolves in
sap. Amino acids in the sap give maple syrup its distinctive flavor, which differs from
pure sugar.
Many people wonder if tapping the tree and taking away so much of the tree’s sap might
harm the tree. In fact, when producers follow tapping guidelines, and tap only healthy
trees, no damage to the tree results. It has been estimated that tapping removes only
10% or less of the tree’s sugar, an amount too small to hurt a healthy tree under normal
environmental conditions.
Average Crown Spread
Average Crown spread is measured in feet. Add the widest and narrowest crown spread
and divide the total by 2.
(Widest spread + narrowest spread) / 2 = Average Crown Spread.
Instructions for “Fast Writes”
 Clearly communicate what the students are to write about.
 Give them a minimum number of lines to write (usually ten
lines).
 Give them a time limit (usually 5-10 minutes).
 Grade assignments on best effort. Very large writing and
statements of topic are not a “best effort.”
 Students should label their paper with the topic, number of
lines required and the time limit.
 Students should skip every other line while writing.
 Students may pose questions if they do not have enough
previous knowledge to complete the assignment with facts.