Oyster card advice! Family trip to London

[QueryA]

We have booked a trip to London for the October school holidays. We’ve not visited London in about 15 years and are completely clueless about the cheapest & easiest was of travelling around. We are there 4 days, staying near Paddington and will be travelling around zone 1 (tower bridge, Tower of London, London eye, madam Tussaud’s)
There is 2 adults, dd (13) dd(11) and ds (9).

I’ve been looking into Oyster cards but I’m completely confused. Does ds need one? How do I get a ‘teenage’ ones for dds? With a family is it cheaper taking taxis? Don’t even get me started on Uber, I’ve not got an account and have never used one!

Any help and advice much appreciated, I feel like such a country bumpkin!

It’s surprisingly difficult to work out the cheapest way to travel.

@Svalberg

The discount can be added there & then at any tube station, gives you 50% discount.

Point of detail - tube stations don't have ticket offices any more

Can I just add make sure if you use contactless that you always use the same card for your journeys in a day. Don't use say card on your phone and then your card. There's a max cap charge per day and if you mix methods you don't get the cap applied. 🧐

toptiplondon.com

All your dc can travel free on buses, but as others have said just use a debit card on tubes/trains

Make sure your kids know to stand on the right on escalators, thus avoiding the locals who will be charging past on the left. Buses are definitely more fun than tubes though.

@SquirmOfEels Sorry, I should have said you just speak to any member of staff who's standing around - thanks