Our activities stay out for a week, role play for upto half a term and larger small world setups for upto 4 weeks. It hasnt been the explaining that has been so much of the problem, more the setting up of lots of areas. We are going to trial changing things over on a rota ie water and mark making on mondays, construction a small worls on tuesday etc. That way there isnt the mad dash to change everything and we wll only have to explain a few things each day. Havent quite worked out the planning though yet as we currently use a weekly overview and obviously somethings will be out for longer in the following week.