Instructions for folding a paper airplane called the Basic Dart were included in a children’s book published in 1859. Image: Shutterstock   Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. By signing up, you confirm you are 16+, will receive newsletters and promotional content and agree to our Terms of Use and acknowledge the data practices in our Privacy Policy . You may unsubscribe at any time. While a holiday weekend has come and gone, May 26 is not without a cause for celebration. It’s National Paper Airplane Day!  The annual day commemorates the homemade aeronautical toy that has fascinated (and frustrated the less crafty) children and adults for generations. According to National Day , the practice of constructing paper planes is sometimes called aerogami, after origami, the Japanese art of folding paper.…