Have items ready to complete and extend patterns.  You can use blocks, poker chips, candy, cards created for holidays, etc.  Hand the materials to your child(ren) and ask them to sort them by likeness.  Ask them to create, duplicate, complete, and/or extend a pattern.  For example, you can hand them a handful of colored goldfish crackers or colored cereal rings.  Once they are sorted, count how many you have of each color. Ask them to select at least 2 colors to make patterns with. Allow them to create more complex patterns as they are ready.