Most children are fascinated by dinosaurs at some stage. Here is another idea how to make a nature walk into a small science project.
Next time you go for your walk, collect twigs, sticks and pebbles of various shapes and sizes. Google a picture of a dinosaur skeleton of your choice (it's complexity could depend on your child's age), sketch it with chalk on the garden slabs or pavement and get creating!
A couple of examples attached, made by my daughter Izzy and her best friend Isobel.