This simple idea kept us busy for about five minutes, but it was a lot of fun.
Henry is starting to recognise a few words from some reading books, so to make sure he's not just learning the book off by heart (rather than reading) we look for original ways to practice the words.
A few months back i did something similar just for letters, on the beach. I use chalk, so it washes away and we can practise new things each time.
I write letters, numbers or words on the floor, then i ask Henry to find a specific letter or number and "JUMP ON IT".
Alternatively i suggest an object and ask him to find its first letter. With the words i asked him to find specific words. Then as a follow up i asked him to randomly jump on words and tell me what they were.