Why is g 10 N/kg?

This a directed inquiry-based learning worksheet I have prepared so students can answer for themselves why g has the value it has. From Year 7 in the English National Curriculum, they are given this value but rarely do we explain where it comes from. This sheet attempts to answer that question. I use it with Year 10 students but it could easily be used earlier or later on in physics. Each questions leads onto the next with minimal guidance required. The stronger students can work through it with ease and move on to a practical where they determine the value experimentally. Weaker students will need more guidance but this activity will allow you the time in class to do this. I have a number of these sheets I have been developing recently and they have been successful with with classes.