One of my absolute favourite websites for practical lesson ideas is teach maths. It is full of free lesson plans across the whole curriculum, more importantly all of the lessons are hands on and practical. So far I have tried two lessons from this site, both of which have been brilliant!
The first of these is on body-surface area, the plan is available here. Basically students have to calculate the surface area of their body. In order to do this they have to split their body into different shapes (I show them the slide above for inspiration) then they take the necessary measurements to calculate the surface area of each shape. This has a lot of real-life applications, the most interesting being calculating doses for things like chemotherapy. Once they have an answer there is a formula which the medical profession use, they can apply this formula to see how close their estimates are.
The second lesson is on discovering the formulae for the volume of a pyramid, the lesson plan is available here. In this lesson students construct six pyramids which they fit together to make a cube. They can then see that the volume of one pyramid is one sixth of the volume of the cube, a bit of algebra later and hey presto the formula for the volume of a pyramid is discovered!
Both of these lessons have worked really well for me, students have been really engaged and more importantly have been forced to think for themselves. Along with these lessons are many other brilliant ideas which I can’t rate highly enough, well worth a look.