A little bit difficult to say and distinguish mass and maths, but Class 2 have had no problem.  Their Maths lessons have been rather physical of late as they have had to measure in a variety of different ways; length, mass and temperature.  I wonder how easy you would find it to estimate and then accurately weigh a piece of Playdough weighing 20g, 50g and then 70g?  Then finding the correct amount of weight to balance this, with only classroom items at hand?