I had a couple of questions about the 'how' of the grid project for my 4th grade (click here). Here is how I broke it down. It was a little confusing for me (the creator) so I hope I can explain how I did the project. Here is my attempt...
Each student is given a grid and a section of the over all image. On each of the images I placed the same grid (I used a clear transparency over the picture to place the same grid on the image when making copies for the kids). I let them place three sections of the image onto the grid (simply to help them line up their drawing.
Using the sections NOT placed down, the students would draw with pencil using the grid.
Now have the kids use their hatching and cross hatching skills (they already practiced how to use a grid and how to hatch and cross hatch the hour before). I encouraged them to used both methods to give a little broken up look.
The students created each 'poster' with 12 sections. They had to place them together as a team with little help from me. It was fun to see them working as a group to figure out the 'mystery' image. I hope this helped! Let me know if there are more questions.