Sustainable castle construction. Lego building. Plants and science and the beauty of recycled materials. It’s all part of the upcoming Seaport Kids x Earth Day lineup of activities hosted by Mommy Poppins and Brooklyn Bridge Parents on Saturday, April 20. Let the kids loose to build and create with recycled moving boxes and other recycled materials. Open their eyes to the wonderful world of plants. This afternoon of Earth Day-inspired crafts, activities, demos, and a Magic Show will plant the seeds for environmental awareness in a hands-on way that’s full of fun.