Rainy Day Indoor Activities
Rainy day? No problem! Get away from the TV - and skip the cabin fever - with animal charades. Compile a list of animals on pieces of paper and place them in a bowl, hat or anything round you can find! Everyone takes turns choosing an animal and acting it out until guessed correctly! (Tip: for added challenge, try with no sounds)
Source: parenting.com/gallery/18-fun-active-indoor-activities?

Think Outside of the Cardboard Box
The possibilities are endless when it comes to cardboard crafts and, better yet, you wont have to bust out the wallet for this activity. From racecars to space ships to forts, oh my! There is so much potential for these crafts, and they are prefect for encouraging the imagination of your little ones - whether it’s indoors or out in the garden.
Source: kidsactivitiesblog.com/52717/30-cardboard-box-crafts

Backyard Camping
Set up the tents and the campfire (or grill). Roast dinner over the grill and finish the night off with smores! (Tip: enhance the magic by camping out during a meteor shower and making your wishes upon the shooting stars)
Source: https://www.care.com/a/101-fun-things-to-do-with-kids-this-summer-1305030150

Lemonade Stand 
There is nothing better than an ice-cold glass of lemonade in the heat of the summer. Use your favourite recipe and set up a stand with your kids; treat your neighbours and passers-by to a refreshing treat! (Tip: Lemonade stands are a great opportunity for your kids to work on their money and math skills. Make it special by donating the funds to a charity you really care about and make a difference this summer)
Source: http://www.thisoldhouse.com/toh/how-to/intro/0,,20210158,00.html

Good Old Fashioned Balloon Fight
Set up an old fashioned water balloon fight – face off one on one or have the whole family join in on the fun and set up teams! It’s the perfect way to cool off and have fun! (Tip: Don’t have a backyard? Bring some friends and head to the park for an epic water balloon battle)
Source: http://poshsitting.com/uncategorized/15-water-balloon-games-you-can-play/

Backyard Slip and Slide
Have an extra tarp lying around? Perfect! Use it to make your very own backyard slip and slide. Hose it down with water and add soap/shampoo – they’ll be slipping’ around in no-time! (Tip: Worried about bumps and bruises? Have them slide down on blow-up air mattresses to avoid injuries!)
Source: http://games.thefuntimesguide.com/2011/06/slip-and-slide-reviews.php

DIY Sandbox
Don’t want to ruin that backyard you’ve spent so much time tending to? No problem! Make a sandbox by taking a plastic storage container and filling it with either store-bought or beach sand. The kids will love it and the lid will keep out the neighbouring cats – what more could you want?
(Tip: Hide treasures and make it a treasure hunt!)
Source: http://www.filthwizardry.com/2009/04/chalk-and-water-painting.html