9 year d boy

I second the National Air and Space Museum. I'd also add the National Zoo Dr NW, National Building Museum, International Spy Museum, Smithsonian Institution: Discovery Theater, a sporting event (Washington Teams: Redskins, Nationals, Capitals, Wizards), Wolf Trap National Park for the Performing Arts , etc. There's lots for kids to do/see for fun!

Air and Space Museum is typically a hit even though it is still history. Check the Smithsonian's website too as I have found that they have had some very interesting exhibits for younger crowds like the Video Game History exhibit that was at Science and Technoloy in the past. Some do living history which tends to draw in the younger children as they get to interact with the displays. The National Spy museum can be good too as you get to take on a spy persona and see just how good a spy you would make.

The National Air and Space Museum is pretty cool. The Museum of Natural History has LOTS of fun stuff for kids to touch, do, see. 

air & space museum  He will love it.

The International Spy Museum is great for kids - and for adults!  And of course the National Air and Space Museum is great for kids if he likes aircraft and spacecraft.

Hi,John! You didn't mention when you would be traveling to DC. Absolutely, the National Air and Space Museum , even if you don't visit the individual exhibits there, just walking through beneath the planes and the rockets is very cool. And be sure to stop in the gift shop for a bag of astronaut ice cream! A big hit with the kids. There is also a very small McDonalds outside the Air and Space on the corner of 6th. Definitely go to the Museum of Natural History There is an unbelievable amount of cool things such as The Ocean exhibit, the Mammal exhibit, Bug and insect exhibit, a butterfly exhibit that you walk through ( this is the only exhibit you will need to pay a small fee to go in) IMAX movies, there are two unbelievable photo exhibits that, believe me, even your 9 year old will find the photos incredible. Really, this museum is where you will spend most of your time. The entire building is unbelievable! The National Museum of American History would be a good stop, too. Check online and pick and choose before hand which exhibits you'd like to see. There are old cars and trains, toys, a very cool house over 200 years old. This place is massive, so it's best to know ahead of time what you want to see. The National Gallery of Art has a sculpture garden that has an ice rink open until March 13th. Even if the ice rink is closed, walk around and view some very cool sculptures ( your son will love the HOUSE sculpture by Roy Lichtenstein) and get a bite to eat in the Café. Have little snacks available throughout the day and walk from the museum area of the Mall to the Washington Monument(closes at 5 through May, then 10PM) National World War II Memorial and Lincoln Memorial. You can also rent bikes if you don't want to walk. I suggest, depending on your timeline, walking at night to the Memorials. They are lit and it is safe to walk the area. They are magical at night. All the Memorials are worth the visit. The Korean War Veterans Memorial is my favorite, very life-like (see photo). Please keep in mind that once the museums close, that end of the Mall will have no bathrooms available. You have to cross the street near the Washington Monument where there are numerous bathrooms open late. Oh, and away from the Mall area, definitely the National Zoological Park

I can go on and on but many things depend on the season you are traveling. Please let me know if you have any other questions. DC is perfect for you and your 9 year old! Travel safe and enjoy!

The National Air and Space Museum is always fun. They also have an annex out at Dulles airport where they house the space shuttle. The International Spy Museum  is also great for kids. For an extra fee they can go on a spy mission. The Nationals baseball games are reasonably priced if you are there during baseball season. The pandas at the zoo are usually a big hit and since it's a smithsonian museum it is free. The natural history museum had a good dinosaur exhibit.

I would consider The White House, Lincoln Memorial, Museum of Natural History. 

Take a boat trip from Old Town Alexandria across the river, under the new Wilson Bridge to National Harbor.  Ride the Ferris Wheel overlooking the water. Visit inside the Gaylord hotel Gaylord National Resort & Convention Center which has a enormous atrium at least five stories tall and ride the glass elevators to the top.  Inside there is a stream running through the atrium, places to eat and musical water fountains. There are gardens and steps down to the river from the atrium.

Boat trip from Old Town BoatU.S. to Mount Vernon Mt Vernon.  Walking up to the house pass the original farm, see all the outside buildings near the house, see the vegetable gardens, skip the house if there are long lines.  There is plenty of room for a nine year old to run off energy. Pick up great stuff to take back to school.  Nice place to picnic in good weather.

Great Falls Park where the Potomac river drops down over huge rocky outcrops and a popular place to see white water kayakers running the river.  There are picnic tables, a place to buy food, an interesting museum of all things in the park.  Great overlooks, one of which gives the opportunity for a nine year old to climb rocks safety.

Visit the Botanical Gardens United States Botanic Garden. There is cat walk up in the tree tops around the huge center glass atrium.   Walk through the different plant environments from desert to humid zones - the walk is quick enough with enough variety and strange stuff to keep a child's interest. There is a cocoa tree in the main area which grows cocoa pods (for chocolate) right off the tree trunk.  Walk across the road and buy lunch in the Indian Museum National Museum of the American Indian.  They sell food from different Indian tribes/geographical areas, interesting and tasty.  On weekends there is often music or dance going on in the main floor area.

National Zoological Park. See the new panda cub and so much else.

The National Air and Space Museum, Museum of Natural History, National Zoological Park (panda cub!) and the Washington Monument  is pretty cool as you go up and elevator inside and get a 360 degree view of DC. Depending on season, there's a carousel in front of the castle or an ice skating rink In the national gallery sculpture garden. Across the river, you can picnic on grass at the end of the Ronald Reagan Washington National Airport runway and watch planes land.  

The Smithsonian (www.si.edu) has an exhaustive list of things to do and a pretty good app for smart phones. Kids love DC!