I call students to the gathering area and remind them of our learning in this unit so far. We have looked at adaptations to the cold. We have looked at different kinds of eyes and how the eye works. Today, we are looking at how animals may adapt to a hot environment.
I ask students to return to their desks and get out their interactive science notebooks. I tell them that I want them to recall what they know about how an eye works and to reflect on how the basic function of a cow eye, might need to change to adapt to a hot environment such as a desert. I provide students with the reflection prompt on a mailing label. They stick them on the page and can refer to it as they write. This reduces the time needed for reflection, as students do not have to copy the prompt.
Before I release students to their writing task, I ask them to brainstorm about desert conditions. We talk about environment, weather, temperatures, and other biome characteristics that are specific to deserts. Once students have a good grasp of what we are talking about in terms of deserts, I send them back to their desks to answer the reflection prompt.
There are many wonderful descriptions of Desert biomes. I chose a reading at http://www.desertusa.com/desert.html, because this description is limited to just the physical description of the biome and does not discuss animal adaptations. Students will read this passage individually and then meet in groups of four to discuss. I use a cooperative learning structure, in the summary process, to help students collect the most important information that is necessary to our investigation today. This structure is called “The Placement”. Each student writes his/her summary in his/her quadrant. after individual summaries are complete, students create a group summary in the center box. This summary can be shared during group discussion time. The graphic organizer for this activity is included with this lesson.
I call students to the gathering area. Each group shares their summary of the desert biome. Using this as a springboard, I asked students to brainstorm animals they might find living in the desert biome. Students might provide answers such as:
Black widow spider
This is not an exhaustive list, but gives some indication of the variety of animals that can be found in the desert. I ask students to close their eyes and envision the desert biome. I ask students to think about the list of animals we made and to distinguish some unique characteristics they may have that allow them to survive in this harsh environment (The two biggest adaptations necessary for survival in the desert are: the ability to store and or find water and prevent water from escaping their bodies).
If students have not come to the realization that water is a primary concern in a desert environment, I steer the discussion towards this concept. I called on two student volunteers to come to the front of the classroom. Each student rolls up his/her sleeves. The students dip one arm into water, while keeping the other one dry. Students wave their arms in the air and make observations.
I ask students to describe any similarities or differences between their two arms. Students will report that the wet arm felt much colder than the dry arm when waved in the air.
I ask students what this simulation might represent in their own bodies. Students may come up with answers such as, feeling cold when getting out of the bath or shower, sweating in the summertime, and evaporation on the outside of the glass of cold juice. All of these examples, along with the simulation, offer examples of how our bodies or other bodies strive to cool themselves in hot environments. Animals that live in the desert are very adept at cooling themselves by sweating and panting.
The above simulation is for an animal with warm blood. I ask student to think about cold-blooded animals such as snakes and lizards that also live in a desert biome. I ask students how these kinds of animals might keep themselves cool. We often talk about cold-blooded animals basking in the sun to keep warm, but we don’t often talk about how they keep themselves cool. Students will answer that they’re cold-blooded and this will help them stay cool. This is true, but these animals must also protect themselves from the extreme temperatures that occur during the day, in a desert. Students may suggest burrowing, lying in the shade, and lying in water, as examples of how cold-blooded animals might maintain their cool temperatures. If students don’t suggest it, I remind students that not all animals will come out during the day. I ask students if they know what the term might be for an animal that only comes out at night (nocturnal).
As a wrap-up to our discussion today, I ask students to sketch a desert biome showing some of the animals and environmental characteristics that are unique to this type of biome. This will serve as a formative assessment for understanding of the concept of adaptation and the content covered in this lesson today.
I call students to the gathering area and we summarize our learning for today. We compare and contrast the learning from today with adaptations to the cold that we have learned about previously. We create a class Venn diagram, comparing and contrasting hot and cold environments and the adaptations that are necessary for survival. I tell students that we will learn about specific biomes in the coming days and talk about other adaptations plants and animals might need for survival in each of these biomes.