Come In Out Of The Cold
Lesson 2 of 9
Objective: Students will investigate adaptations to cold.
RAP - Review and Preview
I call students to the gathering area. I remind them that we discussed different types of adaptations. We talked about behavioral and physical adaptations. I tell them that today, we are going to look at adaptations to the cold.
I ask students, how their own actions differ in winter and summer. I ask them to describe:
I ask students, why these things change with the seasons? I am looking for answers such as, we need more clothes to survive the cold temperatures in winter. We need different food, because cold food is not as much fun to eat in the winter, it doesn’t warm us up. We cannot stay outside as long in the winter, so we play different games. The games we play, keep us active so we stay warm. You can’t swim outside when the water is frozen, but you can skate on it!
I tell students that our adaptation is a temporary one, although depending where we live, we do adapt to the long-term temperatures. For example, when we live in a dry, hot climate, our bodies learn to tolerate the heat. However, when we live in a cooler, wetter climate, our bodies adapt to that. We experience discomfort when we go to hotter climates for a short period of time. Our bodies, and those of animals, have become accustomed to the average temperature we experience on a daily basis.
Today, we will investigate how animals have adapted to function and survive in cold climates.
Students will complete 3 activities to explore this adaptation.
1. Thermoreceptors – No They’re not dinosaurs!
I place three cups of water on a table. I label them, COLD, HOT, and ROOM TEMPERATURE and fill them accordingly. Students use a stop watch to time the immersion of their finger in the water as follows:
I have students work in pairs, one records the observations of the students who is conducting the experiment. They then switch roles.
The student places one finger in the ROOM TEMPERATURE cup and leaves it there for 15 seconds, he/she then places that same finger into the COLD water cup. He/she answers the question, How does that finger feel? Warmer or cooler? He/she records their answers on their recording sheet.
The students then places the same finger back into the ROOM TEMPERATURE cup and waits 30 seconds. He/she answers the question, how does that finger feel? Does it change over the course of the 30 seconds? Does it feel warmer or colder than it did originally?
The student then moves his/her finger to the HOT water cup (ensure that the HOT water is no more than 120 degrees fahrenheit to prevent scalding), and answers the question, how does that finger feel? Warmer or colder?
Extensions: Have students try placing their fingers into the cups in a different order. Does the sensation change?
2. Why An Exoskeleton?
Students will use a thermometer to determine the best type of material for insulating an animal from the cold. They will use cotton, fur, felt, feathers, and plastic.
I fill a bowl with ice and place it on the tables. Students take the initial temperature of the ice and record it on their recording sheets. Students take turns covering the ice with each type of material and place the thermometer on top of the covering to measure the temperature of the covering. Students will observe the temperature at 0 minutes and 2 minutes. They will repeat this for each covering material. The covering that has the warmest temperature is the best protector from the cold.
3. Blubber is Best.
Students will examine how body fat insulates against the cold. Students will observe a can of lard and a pair of rubber gloves. They will answer the question on a class poster, which of these items will keep your hand warmer in a bowl of ice water? Students can answer, lard, gloves, or neither. Students will work in pairs to record the time that it takes for each person’s hand to change temperature in each of the three scenarios:
- The student will immerse his/her bare hand into a bowl of ice water. The timer will start the stopwatch to time how long it takes until the students begins to feel the temperature of his/her hand change.
- The student removes his/her hand and allows it to warm up. The student then places plain rubber gloves on his/her hands. One glove is rubbed with a generous layer of lard. The child places both hands in the ice water and two students time how long it takes for each hand to change temperature.
Students record the times to see which covering kept their hand warmer longer.
Students should feel warmer longer in the glove with lard on it. This lard simulates the fat that animals build to keep themselves warm in colder weather or colder climates.
Words of Wisdom
I call students to the gathering area to discuss their findings. Students share out their group’s results. We learn which covering makes the best protector from the cold. We learn that blubber or fat is the best insulator against the cold.
Finally, I tell students, that temperature is sensed through the skin, through thermoreceptors. The human skin is full of different receptors that sense heat, cold, pain, pressure, etc.
Human skin is full of different receptors that sense heat, cold, pressure, pain, etc. Within the dermis of the skin, there are free nerve endings, called Thermoreceptors, that are responsible for the sensation of non-painful warmth or cold. Thermoreceptors change the voltage across the nerves in relation to temperature. Nerves in response to either warmth or cold, which gives two types of thermometers: those that detect warmth and those that detect cold.
I want to end this lesson, posing a question to students to think about. I ask them, how thermosensation, the way their thermoreceptors fire, keeps us alive? I don’t want to answer this question as I want students to think about it as they research and develop animal adaptations projects later in the unit.
Students record the question and put their interactive science notebooks away.