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This lesson on Cacti is called Cactus Hotel
Social Studies, Science, Language Arts
by Claire E. Gallo
Grade Level 3-4
Note: This is one of three lesson plans on Claire’s Southwest Experience Unit. All 3 can be found together under Social Studies.
Teacher asks the students to review some facts they already know about deserts. Teacher tells the class that they will be looking at cacti today. She tells them that they will also be learning about a special type of cactus, the saguaro cactus.
*describe the importance of the waxy covering on cacti
*identify characteristics of the Saguaro cactus
*name animals that live in Saguaros
Teacher divides the class into groups. She gives each group a cactus to examine. Students will write what they observe in their Response Notebooks. Teacher asks the students what they observed.
Teacher asks the students what the spines might be used for. Students are also asked why cacti do not have leaves like plants/trees in this area. She then explains that trees with broad leaves, such as those in our region, may lose up to 100 gallons of water a day. She asks students why plants such as these could not survive in the desert.
Teacher explains that it is the waxy substance on the cacti’s outer covering, which helps it retain water in the hot/dry desert. She explains that they will be doing an experiment to show how important the waxy covering is. Teacher shows the groups that they will be given 2 sponges, one covered on all sides but one with Vaseline. They will be placing the sponges in containers of water. They will then take the sponges out of the water and leave them a while to dry. Later they will see if the sponge covered in Vaseline retained more water.
Students perform the experiment and then leave the sponges out to dry. Teacher explains that they will be reading about a special type of cactus, the saguaro cactus. It is found only in the Sonoran Desert of southern Arizona and northern Mexico. (This region is located on a map.) These cacti are prized in this region. Teacher then reads the book, “Cactus Hotel”, to the students. She asks comprehension questions.
CHECKING FOR UNDERSTANDING:
Teacher asks the students what they expect to find when they return to their experiments.
Students return to their experiments to see which sponge retained more water. Students will write what they see in their Response Notebooks and discuss their observations with the class.
Teacher asks students what they have learned about cacti today. Teacher previews tomorrow’s desert lesson.
sponges, plastic containers, Vaseline, cacti, water, paper towels, US map
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