If you don’t want your suggestion to be met with groans, first make a plan.  Find somewhere to forage, take a picnic, or lay a treasure trail.

Home-stirred Mud Kitchen…
If you have outside space, you can make a mud kitchen for young children.  At its most basic you need nothing more than some pie dishes, bottles of water, and kitchen utensils.  Then add interesting extras like sand, pebbles (for stone soup, of course), a sieve, and old saucepans.  Let the children pick leaves (herbs) and make some delicious dishes for the bugs and worms to enjoy.  If you have the inclination, you can take this even further.  We’ve seen some delightful mud kitchens made from wooden pallets, old washing-up bowls, and real taps. 

If mud is in short supply then you could make an improvised ‘lab bench’ instead.  Gather plenty of old plastic bottles, jugs of water, cornflour, vinegar, food colouring, and old shirts = all you need to ignite the minds of your little scientists.  Tip teaspoons of bicarb into a bottle and top up with vinegar for a magical reaction.  Mix cornflour with water to make fascinating gloop.  On a warm day, the kids can play at ‘scientists’ outside and learn about colour mixing and chemistry at the same time.

Forage…
Find a walk to join, or have a go yourself.  Once the kids know what they’re looking for, they’ll be able to ramble and pick while you stroll.  Choose something safe and recognisable like blackberries (hard to miss; August-September), wild garlic (easy to sniff out; March-April), or elderflowers (find a reference picture on the internet; May-June).  At home, you can stir wild garlic into a risotto or pasta; make a blackberry crumble; or transform the elderflowers into lovely cordial. 

How to lay an amazing treasure trail…
“Pick your brains, me hearties!
Mend the map, and then
Race to the end… before Bogey strikes again!”
You’ll need some prep time for this one.  An evening to write the clues, and a secret mission the next day – but a treasure trail can be BRILLIANT!   First, write clues that suit your kids’ level of understanding.  For young children, a simple picture clue will be enough (a gate, a front door, or other house or garden landmark).  For older children, a riddle or hint will be good enough.  You wouldn’t want the trail to be over too quickly!  Put each clue in a numbered envelope, then write on the outside where to hide it (the location described in the PREVIOUS clue).   For older children, leave clues with local family or friends.

To increase the challenge, draw a map showing the site of your treasure.  Tear it up carefully, and put one piece into an envelope with one clue. 
“My name’s Pirate Bogey and I’VE GOT YER MAP!
HO HO, HEE HEE!
To get away I went twelve steps down…
Where could I be?” 
Your treasure could be a cardboard box filled with chocolate coins, a picnic basket, or a garden game – wrap it in a plastic bag and bury it, if you have a suitable spot!