Pew Research Center's "The strong relationship between per capita income and internet access, smartphone ownership"

This finding is super-duper intuitive: A positive, strong correlation exists between national per capita income and rates of internet access and smartphone ownership within that nation.

Because it is intuitive, it makes a good example for your class when you teach correlation to your baby statisticians. This graph is  more engaging than your average graph because the good people at Pew made it interactive. You can see which country is represented by which dot. You can also see regional trends as the countries are color-coded by continent/region.

For more context and information on this survey, see this more extensive report on the relationship between smartphone/internet access and economic advancement. This report further breaks down technology usage by education level, age, individual income, etc.

This data is also useful for demonstrating the distribution of wealth in the world and variability that exists among countries in the same region/on the same continent,