Anthony Keane explains why long-term investing is a great gift to give your children. CHRISTMAS is over, the leftover food is starting to turn nasty, and many children's presents have been put in a cupboard, never to be used again. But there is one gift parents can provide that will keep giving for many years - an early start to long-term investing. It is not difficult, and can deliver some massive financial benefits to children and parents alike. In its simplest form, investing is stashing a few dollars a week into a savings account, keeping your hands off it, and watching it grow over many years. Any invested money will work harder when sitting in higher-growth assets such as shares and real estate, but you don't need a finance degree - or big bucks - to get started. The golden rule is just to get started, as soon as possible. This unlocks the power of compound interest, which has been described as the eighth wonder of the world and simply means earning interest on your interest and so on. These days there are countless online calculators that can help show us just how powerful compound interest is. A good one is on the Australian Securities and Investments Commission's moneysmart.gov.au site. Have a play with the numbers and you may be amazed at how seemingly small amounts can pile up over the years. For example, a child investing $5 week of their pocket money, matched by another $5 weekly deposit from their parents, could see it grow to $22,500 over 20 years. All that hard earned pocket money saved up can really pay off in the long run for children. That's based on a 7 per cent annual interest rate or investment return. If we instead base the projection on the average annual return from shares over two decades - 9.8 per cent despite the pain of the global financial crisis in 2008-09 - the result is $32,000 after 20 years. And if the $10-a-week investment begins with a one-off $1000 lump sum followed by $10 weekly deposits, another $7000 is added to the final figure, which becomes $39,000. Compound interest works even better for adults because they usually have larger amounts of spare cash. Someone who avoids buying lunch or cuts out a few coffees each week may be able to save $50 a week, which would grow to $44,000 over 10 years and $160,000 over 20. Investment newcomers may be worried about shares, particularly considering the carnage five years ago when share prices halved. But shares have delivered investors 2.5 times more gains than cash over the past two decades. You don't need an expensive stockbroker to get started. There are exchange-traded funds, available through cheap online brokers, which invest your money in all the stocks on a share market index, such as the ASX 200. The ride may be bumpy, but time will smooth out the scary corners. Giving children an early education about investing not only gives them money, but also gives them a mindset that is common among millionaires all over the world. Those who put away a little away today are able to enjoy life a lot more later on, and afford much bigger presents.