In this current age and Time, it has become extremely hard to keep kids away from something that is widely done like gambling we just have to educate the kids on the fact about gambling and how hard it is to get out of gambling once you become huck to it, and to avoid that kid's needs not to be greedy and should not stake money on games unless if the regular computer games.
You are right, there is no need to hide anything from children this days, one day you will be shocked to find out that they knew about gambling already, someone close to them might have influence them either home or in school, instead it is better to ask them and tell them it is fine they tell you and put them through yourself, my dad did the same, put that fear in me and I am glad he did, if not I would have use a soft hand to handle gambling.
Normally people will only tell you that you can win by gambling but no one will warn you about losing some money.