Choose the 0-99 set or the 1-100 set of number tiles provided .doc, pdf. Alternatively, you may have your own sets of blocks, tiles or cards that the children could use. Let the children try getting started with placing the number tiles on the number grid. Watch how they set about it.
After a little while, discuss different approaches together such as:
Did you try and place the first tile in the random pile on the floor on the number grid first? If so, how did you decide where to put it?
Or did you sift through the number tiles to find one that you know exactly where to place on the number grid?
Which one did you choose?
What was significant about that one?
Which do you think are key number tiles to get in place on the number grid that help you place the rest?
See if the children can devise some good strategies between them and then encourage them to experiment with different ones to see which ones help them put the number tiles back as fast as possible. You may find that different children find different strategies useful. Encourage them to articulate how they know where to put a particular number tile. Encourage explanations that focus on pattern, place value and multiples.
What happens if it is a 50 - 149 number square, for example?
Can you use the same strategies?
What happens if the number square is not $10$ x $10$ but only $6$ squares wide, for example?
How do you know where to place the number tiles now?
Which widths of number square are harder/easier than the $10$ x $10$?
You may like to give some children a number grid where some numbers remain. Some children could work with the number grid up to $50$ or up to $30$. Some children will benefit from having an adult alongside to help them talk about where they want to place particular number tiles.