Since you are so close to Main St - 3 blocks down - try Hot Table right in the building at the corner of Main and Boland Way -across the side street from the Monarch Place. Great sandwiches and salads. It is a short walk - 5 min - down Harrison Ave - cross Dwight St, then the next block is Harrison and Main. There is your Hot Table!!
BTW - while you are at the Sceince Museum, check out the Dr Suess sculptures all over the Quadrangle, then move on to the new Museum at the far end of the Quadrangle. Have fun!!
Dd you also know the Naismith Basketball Hall of Fame is right there too? It is right next to I 91 and they have some great restaurants there too!