Easy and entertaining:
- Take a bucket full of water, and give kids a bunch of
stones. Everyone drops a stone (or a spade full of stones…) in the water on their turn to find out when the water overflows – and then it s time to enjoy the “waterfall”. - Take two buckets/ cups, fill one with water, keep the other one empty. The task is to carry the water over to the empty basket with cloths (sponges may work better?). Where did some of the water go? My younger one had problems with wringing the cloth but had fun getting wet…
- “Paint” the garden furniture with water. How much water do you need? How does it work with brushes in various sizes?
Free But Fun 
We love science games!
One tip: do NOT get your kids to paint the furniture with a paste made by mixing water with laundry powder and food colouring. Unless you are planning to repaint your furniture anyway, then go for it.
:DDDD I can so see the effects of that mixture. Lucky I didn’t experiment quite that much. Yet. You got me tempted to try it somewhere else than my kitchen/ garden :D.
I recommend paper 🙂