Actually, I did this for my daughter simply because I was cheap!
It took less ink if I didn't print the pictures and used half the paper when I did two words per card.
Go to the print button in LR. Under Layout, choose the Half sheet prints (Word & Picture separate). Under Content, choose word only. Under Number of word prints, choose 1. If you have 10 words to print out, just choose the first 5 and print them out. Then turn the paper around and print the other 5. It does take a little longer to flip it around, but it was worth it.
If you print on regular paper, it is hard to flash the cards quickly. Some times I laminated them with clear shelf cover paper (cheap at Wal-Mart). This made them not stick together while flashing. Then I bought some half sheet clear sheet covers (not so cheap at Office Max) I liked these because I could change the words out every week and put them in a small 3-ring binder and flip through them quickly.
Hope this helps!