Its a great idea and well done taking it on
My kid's school do a similar project in 5th class and here is some ideas and problems from it
Make a time line that includes interesting facts as well as actual history e.g. Walt Disney was born in 1901 or pick sports stars etc. Have questions of interest - who is older your grandparents or the movie "The Wizard of Oz" (1939)?
Watch for family dynamics, most of the problems teachers encountered the first time they tried this were around who is family? lack of knowledge about estranged parents, foreign relatives and adoption etc.
I suggested that they ask the children to discuss at home the idea of a family tree before doing work at school, and each to come in with a basic child-parents-grandparents list. Also to choose maybe just one person to research further; this allowed the family dictate who was researched and how far back and hold back on some information if necessary.
It meant that researching just one person (e.g. one of four grandparents) gave similar information for each child to work with.
They did as you suggest look at house size, no. of rooms etc.
The kids wrote down how many rooms in their current home and compared this to their ancestors, whether there was more than one family in a house, how many shared a room, whether they currently do etc.
Information around TV shown first in public in 1925, colour TV in US from 1950, in UK from 1967 and in Ireland from 1969. How many children today have TVs in their rooms??!!
Kids are great sponges and they can be encouraged into history quite easily if it is interesting.
Here are a couple of census returns for 11 year olds in 1901
11 year old Mill Doffer is someone who clears full bobbins, pirns or spindles holding spun fiber such as cotton or wool from a spinning frame and replaces them with empty ones.
11 year old Carriers Labourer most likely working with his father
12 year old apprentice as his father is a farm servant being an apprentice allows William Joseph to better himself and become a printer
Hope that this helps a little bit and best of luck