I don't know what your timeline is, but at my school the hundredth day of the year is coming up next week. So my brain has been whirring and clicking and generating new games for 100 Day. Here are a few things I've been developing and test-driving.
1. Mosaic Hundred Boards
I took a 12 x 12 panel of 1" mosaic tiles that was left over from an art/science project two years ago, and cut it down to 10 x 10. I removed some of the tiles from the backing mesh, but left most of them attached. Then I labelled the tiles with the numbers from 1 to 100 -- black ink for the tiles that are set, and coloured ink for the ones that are removable. I put the whole thing in a pizza box -- a clean one, of course -- because it's the right shape and it's sturdy. This would be beautiful in a wooden tray or a 12 x 12" picture frame, but for now this works.
To play, kids remove the tiles with the coloured numbers and turn them upside down. They take turns flipping the pieces over and fitting them back into the correct places in the hundred board mosaic. To make it more exciting, I set a timer for 2.5 minutes. (There are roughly 30 pieces to place in the board.) Kids work together and race against the clock.
2. Blind Hundred Board
I have a tray with 100 compartments that I made four or five years ago. The tray is wooden, and it is fitted with 100 square plastic wedding favour boxes or lids. Between the tray and the the boxes, I have made a hundred board out of poster board.
Today I filled the tray with cotton balls to hide the numbers, and provided a cup filled with popsicle sticks labelled with the numbers 1 to 100. Kids took turns drawing popsicle sticks and finding the square on the tray that corresponds to that number. They removed the cotton ball from that square. If they had it right -- ie. the number in the square matched the number on the popsicle stick -- they got to keep the popsicle stick and put the cotton ball back. The child with the most sticks at the end of play wins.
You could use pompoms instead of cotton balls, but they'd be more expensive. You could add an element of fine motor challenge by requiring the kids to use tweezers or tongs or chopsticks to remove the cotton balls. The essence of the challenge is that they are able to find numbers up to 100 based on the position and relation of the number to the rest of the grid. They are able to understand tens and ones as they are arrayed.
3. Numberless Hundred Board
Two years ago I did an art project with my class in which we painted a painting with 100 colourful spots on it, in a 10 x 10 array. I have saved one of these and sometimes use it for math.
I ask kids to find the spot that is number 73 or number 42, or some other number between 1 and 100. They need to apply their knowledge of tens and ones, counting down the rows by tens, and across the rows by ones, until they find it. In learning to do this, they also develop a sense of the quantity of a number. How far down the chart it is tells them how big it is in relation to 100. Spatial, relational and quantitative understanding of number is developed when the dependence on numerical sequence is disrupted by removing the numbers.