Exosphere
The exosphere is the outermost layer of Earth's atmosphere. It extends from the top of the thermosphere to outer space. The exosphere is composed of very low-density gases, such as hydrogen and helium, and it is where the atmosphere transitions into the vacuum of space. Despite its low density, the exosphere plays a crucial role in the Earth's atmosphere as it is the layer through which satellites and other spacecraft orbit the Earth.
Key Points to Remember:
- The exosphere is the outermost layer of Earth's atmosphere.
- It is composed of very low-density gases such as hydrogen and helium.
- This layer marks the transition between Earth's atmosphere and outer space.
- Satellites and other spacecraft orbit the Earth within the exosphere.
Study Guide Questions:
- What is the exosphere and where is it located in Earth's atmosphere?
- What are the main gases found in the exosphere?
- Why is the exosphere important for satellite orbits?
- How does the exosphere differ from the other layers of the Earth's atmosphere?
◂Science Worksheets and Study Guides Fourth Grade. Classifying organisms
Study Guide
Classifying organisms 
Worksheet/Answer key
Classifying organisms Worksheet/Answer key
Classifying organisms Worksheet/Answer key
Classifying organisms Vocabulary/Answer key
Classifying organisms Vocabulary/Answer key
Classifying organisms Vocabulary/Answer key
Classifying organisms Vocabulary/Answer key
Classifying organisms
Worksheet/Answer keyWorksheet/Answer keyWorksheet/Answer keyVocabulary/Answer keyVocabulary/Answer keyVocabulary/Answer keyVocabulary/Answer keyThe resources above cover the following skills:
The Living Environment: Students understand that cells are the basic unit of life, that all life as we know it has evolved through genetic transfer and natural selection to create a great diversity of organisms, and that these organisms create interdependent webs through which matter and energy flow. Students understand similarities and differences between humans and other organisms and the interconnections of these interdependent webs.
Biodiversity: Students compare living things based on their behaviors, external features, and environmental needs.
Describe how living things can be sorted in many ways, depending on which features or behaviors are used to sort them, and apply this understanding to sort living things.