What is the best way to give old textbooks to charity?

My siblings & I have collected a fair amount of textbooks throughout the years. We have ~40 from a range of subjects (maths, commerce, physics, mechanical, biology etc.) & need a place to donate them to. I've done a quick google search but a lot of places don't take outdated textbooks & I figured I'd get some anecdotal suggestions. We don't want to just throw them out because it seems like such a waste. Thanks.