1) Preheat the oven to 180C/Gas 4. Combine the pears, water and lemon juice in a 20cm square baking dish.
2) In a bowl, combine the oats, flour, sugar and cinnamon. Pour in the melted butter and stir to make a crumbly mixture.
3) Spread the topping evenly over the fruit. Bake for 45 to 55 mins or until the topping is crisp and browned.