Those half circle protractors were always such a pain to use back in ye olden times. They never gave you exact amounts, and were just a nightmare to use. You had to recheck what you thought was the answer at least three times because you never knew when your results were going to be just one little line off.
While we can’t travel back in time and bring a Digital Protractor with us, you can always get one for your kids. This thing has stainless steel rulers, and will give you precise measurements down to the decimal. Keep in mind that this isn’t just a tool for school. This would be super handy for DIY projects, as you can lock it down to the angle that you need. This protractor only costs about $20, and has a battery that will give you over 3,000 hours of use.