What is the weight of the shipment delivered by Andrea Simons on March 7, 2016?
on March 7, 2016 refers to ship_date = '2016-03-07'
SELECT T1.weight FROM shipment AS T1 INNER JOIN driver AS T2 ON T1.driver_id = T2.driver_id WHERE T2.first_name = 'Andrea' AND T2.last_name = 'Simons' AND T1.ship_date = '2016-03-07'