Fill the 5 pint glass, pour from the 5 pint into the 3 pint glass. now you have 2 pints in the 5 pint glass. empty the 3 pint glass and pour the 2 pints into the 3 pint glass. now fill the 5 pint glass and then fill the final pint of the 3 pint glass by pouring from the 5 pint glass and you'll be left with 4 pints in the larger glass. ALTERNATIVE: Fill the 3 pint glass. Pour the 3 pint into the 5 pint glass. Fill the 3 pint. Pour the 3 pint into the 5 pint until full (1 pint remaining in the 3 pint). Empty the 5 pint. Pour the 3 pint into the 5 pint (1 pint in the 5 pint). Fill the 3 pint. Pour the 3 pint into the 5 pint for a total of 4 pints in the 5 pint glass.