1A. WINTER PHOTOSYNTHESIS (High School)

1B. PHOTOSYNTHESIS IN WINTER (High School and Advanced Placement)

Do winter evergreen leaves carry on photosynthesis?  Students use the iodine starch test to see the results of photosynthesis in geranium leaves exposed to light and dark conditions.  They also test their predictions about possible photosynthesis in winter evergreen leaves using the same technique.  The two activities differ in the complexity of the experimental design.

Topics:  Plant structure and function, photosynthesis.

Special Considerations:  Activity not recommended for middle school use, except as teacher demonstration, because boiling alcohol is used to extract chlorophyll.

2A. WINTER TRANSPIRATION (Middle and High School)

2B. TRANSPIRATION IN WINTER (High School and Advanced Placement)

Deciduous and evergreen plants lose water by transpiration through the stomates, lenticels, and leaf cuticle.  In winter, many evergreen leaves are thickly coated with cutin and stomates may be plugged, so that little transpiration can occur.  The middle school transpiration activity can be done as a class activity or teacher demonstration.  A summer-active geranium twig, and evergreen and deciduous twigs collected outdoors in winter, are sealed in plastic bags for 24 hr. Students predict which plant container will show fogging as evidence of transpiration.  In the high school version, students use potometers to measure transpiration rates in winter evergreens for comparison to typical summer evergreen data.

Topics:  Plant structure and function, transpiration.

3.  WATER CONTENT OF WINTER TWIGS (High School and Advanced Placement)

Plants in winter are threatened not only by cold temperatures, but also by lack of water.  Students make predictions and observations on the relative water content of deciduous and evergreen branches in winter.  The activity focuses on the adaptive value of losing or retaining leaves as strategies for plant survival in winter weather.

Topics:  Plant structure and function, adaptation/evolution.

Special Considerations:  Refrigerator, drying oven, milligram (_-+0.001 g) balance.

4.  TREE TRUNKS AND TELEPHONE POLES (High School)

Trees contain sap in the liquid or solid state depending on the temperature.  Do trees expand and contract with changes in temperature?  Do different species of trees freeze at the same temperature?  In this investigation, students use dendrometers (metal "tree belts") to measure expansion and contraction of tree trunks in winter, using telephone poles as controls to test their hypotheses.

General topics:  Phase changes, plant growth, ecology.

Special Considerations:  Construct dendrometers using stainless steel tape held in a circle by small springs.

5. FREEZING RESISTANCE IN PLANT TISSUES (High School and Advanced Placement)

Students determine the freezing resistance of woody plants in winter by measuring the temperatures at which freezing occurs.  Low temperatures in the laboratory are achieved using a dry ice/ethanol bath; temperatures inside the stem are measured using a digital thermocouple thermometer with a fine wire probe.  In the data analysis, students discuss the geographical distribution and physiology of the species tested.

Topics:  Adaptation/evolution, plant physiology, ecology.

Special Considerations:  Digital thermocouple thermometers, dry ice.

6. A STUDY OF DECIDUOUS WINTER TWIGS (Middle and High School)

In this activity, students not only identify common deciduous trees in winter, but also measure the annual growth rate of each species.  The analysis focuses on growth differences among species, and how environmental conditions may affect growth.  The activity also provides an excellent opportunity to discuss scientific measurement problems such as variability, accuracy, and precision.

Topics:  Plant structure and natural history, ecology, measurement.

7A. IDENTIFICATION OF NORTHEASTERN CONIFER TREES (Middle and High School)

7B. IDENTIFICATION OF TREES BY THEIR WINTER TWIGS (High School)

Learning to use a dichotomous key is a basic skill of special value to students studying classification or natural history.  These activities, which can be done in the lab or field, include dichotomous keys at various levels of difficulty.  The selected keys include only the most common trees, and are easier to use for beginning students.  The complete keys include all native northeastern or western trees for use by more advanced students.  The keys may also be used in conjunction with other winter science activities such as Signs of Life in Winter, Deer Browse, Tree Trunks and Telephone Poles, Freezing Resistance, and Winter Transpiration.

Topics:  Plant identification, classification, and natural history.

8. IDENTIFICATION OF WINTER WEEDS (Middle and High School)

An important concept in biology is that structure is related to function.  The dried remnants of weed species in winter show differences in their fruit and seed structure which are related to their dispersal mechanisms.  Students use a dichotomous key to identify weed samples in the classroom.  They examine the seed structure of each species to determine the probable method of seed dispersal.

Topics:  Plant reproduction, classification, adaptation/evolution.

9. WINTER WEEDS AND SEEDS (Middle and High School)

Winter weeds are the dried remnants of plants from the previous growing season.  In this activity, students identify winter weeds outside, and collect seed samples from a variety of species.  In the lab, students do a germination experiment, relating percent germination to seed size and quantity.

Topics:  Plant reproduction, classification.

Special Considerations:  Old field habitat near home or school.

10. SEED DISPERSAL BY WINTER WEEDS (High School and Advanced Placement)

Students collect and identify winter weeds outside.  They also set out seed collectors for several days to trap wind-blown seeds. Students use structural clues to predict which seeds are dispersed by wind, as opposed to gravity, attachment to animal fur, or through animal consumption.  Later analysis of the seed collectors provides a test of student hypotheses.

Topics:  Plant reproduction, adaptation/evolution, ecology.

Special Considerations:  Old field habitat near school; construct 6 or more seed collectors from large cylindrical containers (such as bleach bottles) mounted on posts and smeared with Tanglefoot^TM (available from biological supply companies).

11A. SEED DORMANCY AND GERMINATION (Middle and High School)

Why do the seeds of most northern plant species fail to germinate in the pleasant weather of autumn?  Students conduct an experiment to compare the percent germination of seeds collected in autumn and stored at room temperature to seeds stored outside in winter.  The activity focuses on the adaptive value of seed dormancy in temperature zone plants that produce overwintering seeds. 

Topics:  Plant reproduction, adaptation/evolution.

Special Considerations:  Collect weed seeds in autumn, storing some indoors and some outdoors until midwinter.

11B. SEED DORMANCY: A STRATIFICATION EXPERIMENT (High School and Advanced Placement)

Students expose seeds of various temperate zone plants to extended periods of cold, a process called stratification. Students then relate percent germination to the period of cold exposure. The analysis focuses on the importance of chilling in breaking seed dormancy and its adaptive value. Topics:  Plant reproduction, ecology, adaptation/evolution.

Special Considerations: Collect weed seeds in autumn, and store indoors until midwinter.

12. SIGNS OF LIFE IN WINTER (Middle and High School)

Is life in winter at a standstill until spring?  This discovery activity provides a quick general survey of plant and animal life in three winter habitats -- field, forest, and pond or stream.  Outside, students look for signs of animal life (tracks, scats, burrows, gnawed plants), listen for and identify birds, collect weed seeds and bark samples, dig under the snow to collect soil invertebrates and green plants, and turn over rocks to collect aquatic invertebrates.  In the lab, students identify plants and invertebrates, and discuss the adaptations that allow organisms to be active in winter.

Topics:  Ecology, natural history of plants, birds, mammals, invertebrates.

Special Considerations:  Access to field, forest and/or aquatic habitats.

13. INVERTEBRATES UNDER THE SNOW (Middle and High School)

Students may be surprised to find that there is active animal life under the snowpack.  Pitfall traps set in the lawn, under shrubs, and other locations near school in autumn should collect a variety of invertebrates after winter snowfall.  Students use a simple key to invertebrate orders to identify and count the number of invertebrates collected from different habitats.  They relate invertebrate abundance data to the depth of snow, plant cover, and other physical conditions at each location.

Topics:  Invertebrates, classification, ecology.

Special Considerations:  Order pitfall traps for pairs of students from a biological supply company, and install before snowfall.

14. WHAT'S INSIDE GOLDENROD GALLS?  (Middle and High School)

15A. MORE ABOUT WHAT'S INSIDE GOLDENROD GALLS (Middle and High School)

15B. GOLDENROD FOOD WEB DYNAMICS (High School)

16. A STUDY OF GOLDENROD GALLS (High School)

These four activities focus on the ecological relationships among the insects inside goldenrod galls.  "What's Inside Goldenrod Galls" is a discovery activity; students speculate on contents of unopened galls before identifying insects in the galls using a simple dichotomous key.  The next two activities investigate population interactions.  Students collect galls at home or school, and count and identify goldenrod gall insects using a dichotomous key. Students construct a food web based on class observations and compare it to known food web relationships.   The difference between these activities is in the method of data collection and degree of analytical detail. "A Study of Goldenrod Galls" focuses on the behavior patterns of the parasites and predators -- including birds -- in the goldenrod food web.

Topics:  Insects, birds, classification, ecology.

Special Considerations:  Pruning shears or paring knives for opening galls desirable.

17A. STREAM INSECTS (Middle and High School)

17B. AQUATIC INSECTS IN STREAMS (High School)

Aquatic insects are active and easily collected all winter.  In the first activity, students use a key to identify insects that they collect from the shallow riffle zone of a stream.  In the second activity, students quantitatively compare samples taken from both riffles and pools of a stream.  In both activities, the analysis emphasizes various insect body adaptations for attachment to the substrate.

Topics:  Ecology, insects, invertebrates, adaptation/evolution.

Special Considerations:  Stream habitat; waterproof boots or waders, rubber gloves, aquatic nets.

18. LIFE IN A WINTER LAKE OR POND (High School and Advanced Placement)

The kinds and numbers of organisms in a winter lake or pond depend on environmental conditions such as temperature, light penetration, and dissolved oxygen. Low oxygen levels are a key factor in winterkill conditions that lead to fish death over winter. In this activity, students sample bottom organisms and measure the physical conditions in a winter lake or pond through a hole in the ice to determine if winterkill condition exist.

Topics: Invertebrates, ecology.

Special Considerations: Lake or pond habitat; ice fishing and aquatic sampling gear, Hach (dissolved oxygen) kit.

19. TORPOR IN GOLDFISH (Middle and High School)

Northern animals have evolved various cold-weather survival strategies, such as hibernation or migration.  Fish and other vertebrates exhibit torpor (reduced metabolic activity) under cold temperature conditions.  In this activity, students lower the water temperature surrounding a goldfish, and count gill cover beats as a measure of metabolic activity.  The data analysis focuses on the adaptive advantages of low metabolic activity in winter.

Topics:  Fish, metabolism, respiration.

20. DEER SCATS (Middle and High School)

In this field activity, students locate a snow-covered area used by white-tailed or mule deer from tracks, scats (feces), or sightings.  Students estimate the population size by using the fact that members of the deer family defecate about 13 times per day.  Students mark off an area and clear it of all scats.  After 24 hours, they count the fresh scat piles; any multiple of 12-13 piles is the equivalent of one deer.

Topics:  Mammal natural history, ecology, behavior.

Special Considerations:  White-tailed or mule deer habitat.

21. DEER BROWSE FIELD STUDY (Middle and High School)

After learning which plants are used by deer, students simulate deer feeding on vegetation in winter.  In a given time period, students collect as much deer food as possible in plastic bags using pruning shears or knives.  In the lab, students estimate the feeding effort an average deer must make to survive a single winter day.  Students obtain a sincere appreciation for the behavioral and morphological adaptations of animals in the winter environment.

Topics:  Ecology, behavior, nutrition, natural history, wildlife management.

Special Considerations:  White-tailed or mule deer habitat.

22. MAKING TRACKS (Middle and High School)

Analyzing animal tracks in the snow reveals much about the kind, number, and behavior of winter-active mammals and birds.  Students learn basic tracking techniques at school by interpreting tracks made by other students in fresh snow.  Then students find, photograph or sketch, and interpret wild or domesticated animal tracks in rural or urban environments near home.

Topics:  Ecology, behavior, mammals.

23. SNOWSHOES TO GO (Middle and High School)

This "fun in the snow" activity is designed to show how some animals have adapted to winter weather by evolution of their body parts.  Northern mammals -- such as caribou, lynx, and snowshoe hare -- tend to have larger feet and longer legs than the deer, bobcat and cottontail rabbits which live further south.  In this activity, students determine if snowshoes are an advantage over boots for humans under local snow conditions.  The analysis uses class data on human movement in the snow with and without snowshoes to understand some morphological adaptations of animals.

Topics:  Adaptation/evolution, behavior, ecology, mammals.

Special Considerations:  Snowshoes for pairs of students (perhaps available from local nature centers, high school or college athletic programs, military bases or local power company).

24A. BIRD NATURAL HISTORY AT A WINTER FEEDER (Middle and High School)

24B. SEED PREFERENCES OF WINTER BIRDS (High School and Advanced Placement)

In the natural history activity, students identify and count birds at a feeder on school grounds.  Students use information on the nesting range (biome) and the feeding habits of each species to determine if the birds are migrants or residents.  In the seed preference activity, two bird feeders are set up on school grounds, one offering sunflower seed and the other offering finely cracked corn.  Birds can eat on top of either feeder, or on the ground below either feeder.  The class is divided into groups which count and observe the birds in the four feeding locations.  Students use combined class data to relate bird feeding preferences to body and bill size.

Topics:  Birds, nutrition, ecology, behavior.

Special Considerations: One or two simple platform bird feeders set up on school grounds 4-6 weeks in advance.

25. POPULATION STUDY OF CHIMNEY PERCHING BIRDS (High School and Advanced Placement

This activity focuses on the behavior of city birds in winter weather.  Pigeons and starlings seem to perch on chimneys when heat gain from the chimney and the sun is maximized and body heat loss to the air is minimized.  Students collect data on the way to and from school on the weather and the number of birds perching on chimneys.  They use this information to determine optimal weather conditions for chimney perching behavior. 

Topics:  Behavior, birds, ecology, heat transfer, weather.

Special Considerations:  Urban environment with masonry chimneys.

26. A WINTER DAY (High School)

This discovery activity provides a general survey of the physical environment near school on a winter day.  Students record air temperature, wind speed, and cloud cover; they dig into the snowpack to measure the thickness, temperature, pH, and density of snow layers.  Students may preserve snowflakes in plastic. Discussion of class data emphasize animal and human adaptations to the winter environment.

Topics:  Ecology, weather.

Special Considerations:  Weather instruments; soil core sampler (used to sample snowpack); formvar solution (1% by weight polyvinyl formal in ethylene dichloride) or aerosol plastic spray (available in art supply stores) for preserving snowflakes (optional); construct snow samplers (soup cans open at both ends with wooden handle)

27. MINIMUM TEMPERATURE (High School and Advanced Placement)

The minimum temperature in a 24 hour period can differ by several degrees from place to place, even within a small backyard. This temperature variation may seem insignificant, but to a rabbit or bird seeking shelter for the night it can be a life or death difference. In this activity, students consider the exposure to daytime sunshine, the vegetation and snow cover, and the topography to predict where the highest and lowest minimum overnight temperatures might be recorded. They place min-max thermometers in a study area near school to test their hypotheses.

Topics: Heat flow and capacity, weather, animal behavior.

Special Considerations: Suitable study area, two min-max thermometers for each student group.

28. SNOW TERMINOLOGY (Middle and High School)

To many people, snow is just a nuisance to be shovelled, plowed, melted, or tolerated so that everyday life can go on in winter.  But the Inuit people (Eskimos) named dozens of kinds of snow, recognizing the importance of snow to the survival of plants, animals and humans in the northern environments.  In this activity, students make close observations of snow conditions, using Inuit terms to describe differences in hardness, texture, and crystal structure.  The purpose of this activity to understand the ecological significance of differences in snow conditions while using an interesting new vocabulary.

Topics: Ecology, weather.

29. WHEN DOES IT SNOW?  (Middle and High School)

Snowfall is a major component of winter weather, affecting the survival of plants and animals as well as influencing human activities.  Students keep a weather log for several weeks, measuring snowfall, air temperature, relative humidity, pressure, wind speed and direction, and classifying cloud types.  The data analysis focuses on identifying atmospheric conditions consistently related to snowfall.

Topics:  Weather.

Special Considerations:  Weather instruments.

30. CAPTURING SNOWFLAKES (Middle and High School)

Students use liquid plastic to make replicas of snow crystals. Students collect snow crystals in the air and in the snowpack to observe changes in crystal structure with time. As an option, students speculate on the range of temperature and humidity conditions in the clouds producing the crystals they collected.

Topics:  Crystal structure, weather.

Special Considerations:  Formvar solution (1% by weight polyvinyl formal in ethylene dichloride) or aerosol plastic spray (available in art supply stores)

31A. SNOW LAYERS (Middle and High School)

31B. SNOWPACK STRUCTURE (High School)

These activities focus on the physical changes that occur in snow on the ground.  Students go outside to observe and identify various layers in the snowpack.  In the middle school activity, students predict and then measure where the temperature will be warmest in the snowpack.  In the high school activity, students also predict and measure density of snow layers in the snowpack.  In both cases, students use what they know about temperature gradients and water vapor movement to explain the changes they observe in the snowpack.

Topics:  Crystal structure and metamorphosis, density, heat flow, phase changes, vapor pressure.

Special Considerations: For high school activity, construct snow samplers (soup cans open at both ends with wooden handle).

32. ACID SNOW (Middle and High School)

Acid precipitation is a major environmental problem in northern USA and Canada.  Acid snow accumulates in snow banks all winter; spring thaw may result in "acid shock" to plants and animals at a vulnerable stage in their life cycles.  In this activity, students determine the pH of surface snow in various locations near school.  Students also determine the pH of snow layers in the snowpack, relating this data to the geographical source of recent snowstorms.

Topics:  Weather, ecology, acids and bases.

Special Considerations:  Regions subject to acid precipitation; pH meter of pH color comparators (available through science supply companies) desirable.

33. LETHAL SNOW (Middle and High School)

This activity provides a test of the ability of different minerals to neutralize acid precipitation.  It can be done as a student activity or teacher demonstration.  Containers are lined with limestone (CaCO₃) or granite (SiO₂) to simulate lake conditions.  The pH of snow collected outdoors is measured.  Equal quantities of melted snow are added to each container for the 24 hr neutralization test.

Topics:  Minerals, acids and bases, ecology.

Special Considerations:  Regions subject to acid precipitation; pH meter or pH color comparators (available through science supply companies) desirable.

34A. ICE CREAM AND ICY ROADS (Middle and High School)

34B. FREEZING POINT DEPRESSION (High School and Advanced Placement)

Students measure the freezing point depression caused by adding a salt to a solvent as they make edible ice cream popsicles.  In both activities, salt is added to snow in a container holding a new test tube filled with a cream mixture; the temperature of the salt solution is recorded until the ice cream freezes solid.  In the high school activity, students also compute the theoretical molality of the salt solution (based on the measured mass of snow and salt) and the apparent molality (based on the measured freezing point depression T and the molal freezing point constant K_f) to determine the percent ionization of the salt in solution.

Topics:  Chemistry, freezing point depression, vapor pressure, phase changes, solutions, concentrations.

Special Considerations:  New test tube for each student.

35. FROZEN DIRT (High School and Advanced Placement)

One of the important sources of warmth in the winter environment is the earth's surface.  When the air temperature begins to drop, the soil near the surface cools; the water in the soil may freeze.  Frost depth depends in part on the insulative value of the snow on the ground.  In this activity, three frost gauges are installed in autumn near school.  For several weeks before collecting data in midwinter, students clear the snow away from one gauge and compact the snow around another gauge, leaving the remaining gauge undisturbed.  At each location, students measure the frost depth, snow density, and snow thickness; they calculate the insulative value of the snow cover.  Students discuss the impact of natural snow conditions, and the potential impact of snowmobiles and skiers, on plants and animals under the snow (see Invertebrates Under the Snow).

Topics:  Heat transfer, insulation, earth energy balance.

Special Considerations:  Construct and install frost gauges using three lengths of 1" PVC pipe and 3/4" clear polyethylene tubing.

36A. WINTER HOT SPOTS (Middle and High School)

36B. UNDERSTANDING MICROCLIMATES (High School)

To the casual observer, the winter scene appears to be frozen, white and unchanging.  In reality, evidence of the dynamic processes of heat transfer and wind action can be readily observed and recorded by students with cameras or drawing materials.  The middle school activity focuses on explaining common examples of winter heat transfer (icicles, first frost); the high school activity adds snow drift and snow scour phenomena.

Topics:  Heat transfer, Bernoulli's principle, microclimates, weather.

Special Considerations:  Student access to photographic equipment desirable.

37. QUINZHEE (Middle and High School)

The best known snow shelter, the igloo, is made by the Inuit people (Eskimos) of the tundra from blocks of hard-packed wind-driven snow.  Snow in the tree-covered taiga remains loose; here, the Athabaskan Indians make an alternative snow shelter called a quinzhee, or powder snow cave.  In this activity, pairs of students construct a quinzhee at home, documenting their experience with photographs or sketches.  They measure the air temperature outside, and the temperatures in various locations inside the quinzhee after occupancy.  Students discuss the insulative value of snow, and heat transfer within the quinzhee.

Topics: Insulation, ecology, heat transfer, survival, weather.

Special Considerations: 30 cm or more loose snow.

38. MODEL QUINZHEE (High School)

In constructing a quinzhee, a pile of soft, loose snow becomes hard enough to build a sturdy snow shelter.  This activity focuses on the physical changes -- temperature gradients and the movement of water vapor -- that lead to sintering or fusion of snow crystals within the snow mound.  Students measure the temperature of snow on the ground, and they compare the hardness and temperature profile of an old snow mound with that of a freshly constructed snow mound.

Topics: Crystal structure and metamorphosis, phase changes, vapor pressure.

Special Considerations: 20 cm or more loose snow.

39. WINTER CLOTHING (High School)

There is a science to choosing the right kind of clothes in cold weather.  Different fabrics have different moisture transfer characteristics and different insulating properties.  In this activity, students "dress" cans of warm water in cotton and wool fabric. They test heat retention of covered and bare metal cans under dry, moist and windy conditions.  Students discuss the results of their multiple factor experiments from a scientific and a survival viewpoint.

Topics:  Insulation, heat transfer, evaporation, survival, weather.