Another variation is to ask the child to draw. First make some sticks, circles, squares, or other shapes on a page, and encircle them. Make for the child a big "bubble" to draw in, and ask the child to draw either the same amount, one more, or one less. Also have your child practice writing numbers on paper.
As well as a printed blank hundred square, another way to visualise decimals is to make a decimal stick. Get a cane or long stick, place with tape a number 1 to the right hand end, then a 0 to the left. Ask them now to place 0.5 in the middle, then together work out where all the other decimal points should go.