How to get around Amsterdam with kids - Help!

I wouldn't bother with the OV Chipkaart for the limited number of trips you'll be making.
Buy your tickets from Schiphol to Hoofddorp on arrival, either from one of the machines or at the ticket window. They should be around EUR 2,50 per person.
Hoofddorp to Amsterdam is around EUR 10 return trip for the grown-ups, and a mere EUR 2,50 for the kids, using a Rail Runner ticket. To the best of my knowledge Hoofddorp is an unmanned station, and you'll be dependent on a machine to get those tickets. A safe way to get those, is probably to buy them on arrival at the ticket window on Schiphol.
Others should inform you on the city transport within Amsterdam. But it is a compact city: you can cross the historical centre in half an hour or so, and walking is the best way to enjoy it.
I strongly advise you against cycling in Amsterdam, especially with your children. It is a living city with a lot of traffic, and not a playground for trying out a bicycle.

Your hotel is close to Hoofddorp station.

for the first day:
buy for the adults a single ticket from Schiphol to Hoofddorp (EUR 2.30 + EUR 1 when you buy the ticket at the station).

For the children you can buy a Railrunner ticket (https://www.ns.nl/producten/en/meest-gekocht/p/railrunner) for EUR 2.50.

If you buy your tickets online via https://www.ns.nl/producten/en/losse-kaartjes/p/enkele-reis (thus saving EUR 1), you can buy a single ticket for the children as well (20 cents cheaper than a Railrunner ticket).

The next two days:
For the adults you will need a return (roundtrip) train ticket Hoofddorp - Amsterdam Centraal, which costs EUR 10.20 (+ EUR 1 when bought at the station). For the trams/metros/buses you can buy a 48 hour GVB pass, which costs EUR 12.50 (total: EUR 32.90 + EUR 2 fee)

Another option for the adults is the Amsterdam and Region Travel Ticket. For two days this ticket costs EUR 26. This ticket is valid on all public transport in and around Amsterdam (also the train to Hoofddorp). Buy this ticket the first day when you arrive at Schiphol, but do not use it for your first trip to Hoofddorp. https://www.ns.nl/producten/en/uitleg-overige-producten/p/amsterdam-region-travel-ticket

For the children you can buy each day a Railrunner ticket (which is valid forn 1 day on all Dutch trains) for EUR 2.50 and a GVB childrens ticket for EUR 3.75 which is valid for 24 hours on all metros, trams and buses operated by GVB in Amsterdam.

last day:
The first train to Schiphol departs at 05:25. If you need to be at the airport before that you can use a taxi or Uber. Train tickets can be bought at Hoofddorp station (ticket machines only) or via ns.nl.

No need to buy an anonymous ov-chipcard.

By the way... Remember to check in your tickets at Schiphol station. Schiphol does not have ticket barriers only some small validators. Hoofddorp and Amsterdam Centraal do have ticket barriers. When using an e-ticket (on paper or in app) then there is no need to check in at Schiphol. You do need the QR code on the tickets however to open the ticket barriers at Hoofddorp.

Thanks for the help Floris. Actually I was also looking for some suggestions on it as I am travelling to Amsterdam next week.

I strongly advise you against cycling in Amsterdam, especially with
your children. It is a living city with a lot of traffic, and not a
playground for trying out a bicycle.

I'll second that. You'll see what we mean when you get there but Amsterdam is no place to pedal without experienced background riding in dense BIKE/city traffic, especially not kids. The only place I'd consider it for them might be Vondelpark.

Also, if you didn't get your Anne Frank House tickets online some time ago, I'm afraid you won't be visiting that one: tickets are sold out for the next couple of weeks.

I wanted to thank you all for your help.

I did take your advices and got around great using NS railway. We didn't take the tram as we found the city small enough that we could walk everywhere. We had a lot of fun walking around the Dam Square and little shops nearby.

Anne Frank's house was our highlight. It is definitely a must do. I also took your advice and did NOT ride the bicycle around the city. But we rented bikes right outside Vondelpark and rode the bikes inside the park. That was very refreshing and a lot of fun!

We did not go to a single museum on our stay as we were all weary of museums after London and Paris.

Again, thank you forum members for help. You never fail! =)

Really glad you had a good time!