Today we played War. Yeah, the card game.
Preschooler played "normal" war. Each player flips a card. Whose is bigger?
Grade schooler played addition war. Flip two cards. Add them. Now add my two. Whose sum is bigger? (This also works for subtraction & multiplication.)
Middle schooler played "Integer War." Flip two cards up. Black are positive, red are negative. Add them. Now add my two. Whose sum is bigger?
Another variation for 5th or 6th grade would be to increasing the flip number to three or more, and work on order of operations (red are multiply, black are add), squaring, or using the smaller of two as an exponent for the larger.
If you want to throw some physical exercise into the mix, lie down, keep the cards in your hands & do a sit up before you can play your card(s).
Who says you can't have fun learning, especially in the summer, when you get to make up your own rules?
What fun rules will you make up today?