We learned about pollution and how run offs help it and how we can stop it. First we created a green house, ours worked but had a small leak. Next time I will be cautious. We also made a new type of pavement. It had to absorb water and make sure a wind-up toy could walk on it. We used cheesecloth as our main ingredient, it worked but next time I will try to make it more realistic. The last thing we did was make a city and tried to protect the river from pollution without going over the budget. Ours worked mostly, next time I will not be too afraid of going over budget.