Cardiff museums are a delight to visit, breaking away from the general image of being reserved and mundane. If you want a good example of this then try Techniquest here you get an opportunity to enjoy yourself in
science and technology from the inside. There are some excellent shows and
demonstrations to experience and the planetarium is one of the best.
You can get a season ticket and it works out a very inexpensive way to enjoy this experience with everyone learning something new.
The National Museum of Wales is centrally situated in Cardiff and like all museums is free. One of the best exhibits is the dinosaur exhibition. Cardiff kids can take advantage of the worksheets to explore the museum more thoroughly and remember it is really easy to loose track of time.
In the summer you can enjoy a picnic in the gardens outside.
The museum is frequently home to some excellent art works and exhibitions as well as being home to a few truly massively impressive art works.
Also free and a unique museum is the Museum of Welsh Life at St Fagan’s. Buildings from all round Wales have been moved stone by stone, brick by brick to the museum and rebuilt. When you visit it is hard to believe they weren't built in situ!
There are exhibitions of welsh culture (it's clothing, farm tool and machines and pottery).
St Fagans makes for a great day out. Visit the bakery which is always popular, or the pottery throwing classes where children can learn to throw a pot. Do this early so the pot dries and can be taken home afterwards.
Visit the castle, look at the school rooms and learn about how we used to learn. The teashop is excellent for refreshment with tea and cream cakes! (The one on site is more fun as the entrance cafe gets quite busy.
Entrance is free but parking isn't !