Below are a few different museum links that can be useful for elementary school teachers. At each museum they use different tools and resources that could be used by the teachers in other subject areas through art. Art is a good way to visually stimulate a child's mind and help them better understand the concept you are trying to teach.
Jumping In Art Museums
This museum had some really cool online photos that were taken of people inside of museums jumping. They also had students come in and were traced on a piece of paper of them jumping. They were then told to paint their jumping figures. This type of exercise could be used in a math setting because the students are learning about proportions.
Counting on Art
At the NGA classroom for teachers and students, there are different links you can click on to go to different lesson plans for teachers to use. The one that I chose specifically included a student activity that involved having the students "read" a piece. Basically interpret what they see and what is going on in the piece. This may be used in English, say the students were reading a book that had pictures in it. They could interpret what was going on in the story by reading the piece.
Brookgreen Gardens
At Brookgreen Gardens they have a ton of space dedicated to all the gardens and personally I believe that deciding where to put all the flowers and how to arrange them is certainly an art form. student could learn from this not only from art but they could also use it in science and learn about flowers and what they're made of.
Hirshhorn Museum
At the Hirshhorn Museum they have different types of workshops available for people to take to learn more about different types of art forms and gain a better understanding with different mediums and how to use them. Teachers could make different types of workshops in their own classroom. For each day of the week they could do a different workshop for a different subject that way they can integrate art into different subject areas.
Walters Art Museum
At the Walters Art Museum they offer a bunch of different online activities that involve art with every other subject area. The one that I chose was mathematics. They show a picture of a clay tablet from ancient Mesopotamia which is the art aspect as well as history. They used these tablet in order to keep track of time, therefore also adding the mathematic aspect to this exercise. A bunch of different subject areas are easily integrated with art.