Not too long ago, my grandson and I took a little weekend field trip. We passed one of the precast plants where they were making walls for a prison when he asked what they were doing. How do you explain to a 9-year-old boy thatthey have to make these walls strong enough to keep people inside a prison from boring through and escaping?

He asked if we could get a little closer when I told him what they were for. He wondered about the windows and doors, and he asked if they can make secret passageways like they do on TV.

After a 30-minute discussion on placing "those metal sticks in the wall" and the bars in the windows, he asked, "Could someone pay you not to make the concrete so strong so someone could cut through the walls with a pocketknife and get out?"

I tried to explain that if the walls weren't so thick, they still couldn't cut through them with a knife. The next question was inevitable: "Why?"

Then they were using a crane to load one of the walls onto a flatbed truck when he asked if they were really heavy enough to keep the wind from knocking them over. And how did they stick them together? About this time, I asked if he was hungry and suggested a burger and soda.

We were in a fast-food restaurant, and about halfway through the French fries, he asked, "Where else do they have to make the walls so strong that you can't cut through them?"

The couple seated at the next table looked perplexed at the question and strained to hear the conversation. My next thought was how to explain the details of putting this big concrete puzzle together.

Recalling Legos

Then it came to me: Legos. I played with them when I was his age, and even though he had his electronic games with him, I suggested we go shopping for something that would help him understand. Two hours and $22.99 later, we were on the den floor making ourselves a little prison out of those pesky little building blocks.

Showing him the interlocking pieces, I told him that this was how the walls were put together. Of course, this brought back memories of when my sons played with these demons. I say demons because my most recent memory of them was stepping on them in the middle of the night when I came downstairs to get a drink of water or raid the refrigerator.

We got everything done except the roof when his mom came in. "We're building a prisoner's house," he said. Of course, mom and grandmother wanted to know where this came from, and I just simply told them that it would take too long to explain.

He spent the night with us, and the next morning when I came downstairs, there he sat in the middle of the den floor with all of the blocks almost put together. But there was something different about this building.

I asked who the little green man was inside, and he told me that it was GI Joe. "That's what happens to you when you don't eat your vegetables," he said.

I'll remember that the next time I fudge on eating the green beans.

Jimmy Ambrose