How to use:
Look at the word and guess the spelling of the plural. Tap or click on the word to check the answer. Then tap the "X" in the corner of the answer box or click anywhere outside the answer box to make the answer go away. Then click "New Word."
Kaboom! In groups, each player gets a point for each plural they spell right; if the Kaboom! comes up, the player loses all their points and starts counting from zero again. They can just say how they'd spell the plural and keep track of points with chits (paperclips, whatever); or they can write their answers and keep score on a worksheet like this.
Tech support note: If the network is slow, one might sometimes get a "This page does not exist" or "Can't find that page" error after clicking "New Word." Just swipe right or use the back arrow to go back to the previous word/page, then click "New Page" again.