In order to effectively teach a lesson on the cryosphere to my elementary students, I would use a combination of information found at the three websites below.
First, I would have the students read through and discuss the information provided by the National Snow and Ice Data Center (https://nsidc.org/cryosphere/allaboutcryosphere.html), which succinctly answers the questions of what the cryosphere is, where it is located, and why it is important. Additional information about continental ice, glaciers, and sea ice can also be found at https://earth.rice.edu/mtpe/cryo/cryosphere.html. I would have the students look through this site if they are in need of additional information or explanation.
Finally, I would show the students images of the current state of our cryosphere on The Cryosphere Today website. This site provides statistics and animations that illustrate the changing state of the polar ice and sea caps in the Northern and Southern Hemispheres. The students could view the 30-day time lapse animations and analyze the data illustrated in the charts to make predictions of what the cryosphere will look like in five years, twenty years, and so on.