Tolerance to ADD medications can occur. ADD medications can help increase the levels of neurotransmitter in the synapse.
Nonmedical use of ADD medications can cause symptoms known as "the crash" after the initial flood of neurotransmitter wears off.
ADD symptoms may be caused by altered levels of neurotransmitter.
Amphetamine use can cause increased alertness and mental focus.

Zoe decided to measure the hand length of each of her classmates. first she marked a line across each student's wrist and lined up a ruler from this mark to the top of the middle finger to measure the length. then she recorded the measurements in the table below. marla did this the same way for each classmate, and then zoe used this ruler to measure each straight line and record the data below. this data is invalid. what is the most likely reason why it is invalid? the ruler is marked in centimeters, but zoe recorded data in inches. the range of lengths is too wide, so zoe must have misread the ruler. marla’s complicated measuring procedure was overly confusing. marla could have been inconsistent while drawing outlines of fingers.

Are the earth's ocean floor and continents the same age geologically? why or why not?

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?