1. TIC-TAC-TOE: Draw a Tic-Tac-Toe board on a piece of paper. Each player decides what their "mark" wil be: instead of X's and O's, choose NUMBERS that you would like your child to work on (ideally choose 2 numbers your child cannot already easily identify. Take turns drawing marks until one person gets three in a row.
2. ONE TO ONE CORRESPONDENCE: Gather a group of small items (paperclips, fruit snacks, cheerios, anything small really). Write a number on a piece of paper/post it note, etc... and have your child pick out and place that many of the items under the number - counting out loud as they place them. After they have counted the items, ask your child "How many are there"? and have them point to the written number as they answer.
3. ROTE COUNTING: This is a good activity for times your child is "waiting" (in line at the store, buckled into a car seat, etc...) Ask your child to count as high as they can. Be sure to chime in with prompts (if they get stuck on 15 - you say 16 and wait to see if they can go further. If they are still skipping numbers, count with them. Make it fun and see how far you can get between things. For example; "I wonder if we can count to 20 by the time we reach the McDonalds up ahead". If you are at home, have the child perform an action and count to a designated number; "Let's clap our hands 10 times".