The writing weigh is designed to tackle students understanding of weight as well as helping them apply VCOP to improve their extended writing, essays and compare and contrast skills. This activity also gives students a chance to practise their addition skills.
The resource works on the basis the heavier the assignment the more sophisticated the answer is. Teachers should set a minimum weight for the assignment, which can easily be differentiated for groups of students. When setting the weight use kg instead of g so pupils have to remember 1000g = 1kg. Students then self or peer assess their work using the mat and totalling the weight of their assignment. This mats may also be useful during DIRT or POW time, when students need to respond to feedback.
I would advise laminating a class set of these to save on printing.