If Mr. Jones did an experiment to test the effect of amount of sleep on grades in school, the grades achieved by students would be the HB1A3 theory

independent variable

control

dependent variable

When analyzing tree rings, what do scientists assume a thin ring indicates?

African penguins, which inhabit the coasts of southern africa, were classified as an endangered species in 2010. two significant threats to their survival are ecosystem damage from oil spills and overfishing by humans. overfishing depletes the food supply of african penguins. the best method to reduce the threat of overfishing would be to . the risk of oil spills could be reduced by increasing the use of , which should oil consumption. if an oil spill does occur, could be used to remove the oil so the ecosystem may more quickly recover.

What type of pollution does household garbage cause