You should already know how at least a little bit bout 
In its early stages, PIVX privacy relied upon CoinJoin, the foundation for Dash’s PrivateSend technology involving coin mixing. This feature allows for transactions to be mixed and divided in order to obscure the source. Further along in its development, the project shifted to utilize a customized implementation of the Zerocoin protocol — a product of the Johns Hopkins paper, Zerocoin: Anonymous Distributed E-cash From Bitcoin. Simply put, the protocol works by including a private second currency in transaction blocks, alongside the original currency. These essentially untraceable secondary coins are minted with an obscured origin, and can later be spent on the blockchain without revealing destination or amount. For PIVX, this secondary currency is zPIV — which is of equal value to PIV and carries no data concerning the coin’s history.
Currently over 20% of the PIVX supply is in the form of zPIV. This was achieved through clever incentives by giving 50% extra staking rewards for staking zPIV. This is unparalleled in the cryptosphere with the exception of coins like Monero which doesn't allow non-private Tx.
“Imagine your friend is colour-blind and you have two balls: one red and one green, but otherwise identical. To your friend they seem completely identical and he is skeptical that they are actually distinguishable. You want to prove to him they are in fact differently-coloured, but nothing else, thus you do not reveal which one is the red and which is the green. Here is the proof system. You give the two balls to your friend and he puts them behind his back. Next, he takes one of the balls and brings it out from behind his back and displays it. This ball is then placed behind his back again and then he chooses to reveal just one of the two balls, switching to the other ball with probability 50%. He will ask you, “Did I switch the ball?” This whole procedure is then repeated as often as necessary. By looking at their colours, you can of course say with certainty whether or not he switched them. On the other hand, if they were the same colour and hence indistinguishable, there is no way you could guess correctly with probability higher than 50%. If you and your friend repeat this “proof” multiple times (e.g. 128), your friend should become convinced (“completeness”) that the balls are indeed differently coloured; otherwise, the probability that you would have randomly succeeded at identifying all the switch/non-switches is close to zero (“soundness”). The above proof is zeroknowledge because your friend never learns which ball is green and which is red; indeed, he gains no knowledge about how to distinguish the balls.”
And that's how you prove something without giving up information. Use this knowledge to educate your fiends. It's a simple example that even a child could understand that gets the job done.
Happy Learning!
