In the seven years that I’ve been writing this column, I’ve received many letters from prisoners. Most of them are in federal and state institutions in Pennsylvania. But since the column runs in papers around the country, I get them from other places, too. The following came from a prisoner at the Louisiana State Prison at Angola.

“Sir, I have a 5-year-old son and I wanted to invest a portion of my prison earnings into my kid for his future. I am in need of some advice on how to invest, and what will be the best future investment for my son.

“I do not make a large amount of money. I would say $100 a month is what I earn. Even though it’s not very much at all, I still would like to invest about half, which is $50 a month, into my son for his future.

“Mr. Brown, me, myself, personally, I have never owned a bank account in my life, simply because I did not have the knowledge …

“So this is why I want to open some type of account for my kid, to try and help secure his future even though I’m in prison.”

Here’s my reply:

These days, it’s hard to make much money on any investment. Doing it with a small sum is especially difficult because of the high fees you may be charged for having a small account or for buying or selling investments.

There are many ways to invest for children, depending on your goals. It may be necessary, or helpful, to ask someone you trust to open an account for you, or in your son’s name.

If the idea is to build up some savings for an emergency or unexpected expenses, use a checking or savings account at an ordinary bank. Your money will be safe, and you’ll be able to get it out any time you want.

Unfortunately, the interest paid in most savings accounts is now below 1 percent a year. That means you’ll get less than a penny a year for every dollar you save. Inflation the rising cost of things we buy is more than 1 percent a year. So, over time your money could lose value, in terms of how much it can buy. But that would happen very slowly.

If you don’t think your son will need this money on short notice, you could buy a certificate of deposit at a bank. The longer you’re willing to tie up your money in a CD, the higher the interest rate you will earn. You should be able to get 2 percent or 3 percent a year this way, perhaps more. But you will be charged a penalty if you take your money out early.

Many people with young children put money away for college. For a 5-year-old, stocks or stock mutual funds can be a good investment. Prices of stocks, which represent ownership in a company, can go up and down a lot over short periods. But the average stock makes money over a long period more than a savings account.

With an investment of only $50 a month, individual stocks are out. Trading commissions fees charged when you buy and sell would chew up too much of your money. And you don’t have enough to buy a variety of stocks to spread your risk around.

For many inexperienced investors, mutual funds are a good solution. A stock fund is a company that owns dozens of stocks, sometimes hundreds of them. And the fund’s manager does all the hard work of finding good stocks to buy for the fund.

Some funds require as little as $250 to start. But fees on these accounts tend to be a bit high generally about 2 percent a year. That means if the fund earns 5 percent a year you only get 3 percent. Given these expenses and the risks involved, stock funds probably aren’t for you.

So I suggest you look at U.S. Savings Bonds, which are sold at many banks. They cost only $25 and they are very, very safe.

And right now the EE Bond, also called the Patriot bond, pays nearly 4 percent. That amount will automatically go up if interest rates rise. Also, there are no fees.

You can get your money back after six months, though you’d lose three months’ interest if you cash in the bond during the first five years. If your son cashes in the bonds to pay for college, all the interest built up over the years will be tax-free.

And he’ll know he had a father who loved him.