Indeed, U.S. courts have ruled that ideas of creation science are religious views and cannot be taught when evolution is taught. This question reflects a narrow view of how science works. Things in science can be studied even if they cannot be directly observed or experimented on. Archaeologists study past cultures by examining the artifacts those cultures left behind. Geologists can describe past changes in sea level by studying the marks ocean waves left on rocks.
Paleontologists study the fossilized remains of organisms that lived long ago.
Hypotheses can be made about such phenomena, and these hypotheses can be tested and can lead to solid conclusions. Science is practiced in many ways besides direct observation and experimentation. Much scientific discovery is done through indirect experimentation and observation in which inferences are made, and hypotheses generated from those inferences are tested. For instance, particle physicists cannot directly observe subatomic particles because the particles are too small. They must make inferences about the weight, speed, and other properties of the particles based on other observations.