The town’s annual Fourth of July celebration is again being organized by the Sherborn Fire and Rescue Association, and will include a day full of activities and competitions for the entire family. Activities start with registration at 8:30 a.m. Wednesday, and field games starting at 9 at Laurel Field off Main Street. Events will include foot races and a greased pole competition in which teams can test their skills climbing an 18-foot pole smeared with Crisco, according to Mark Knapp, a firefighter who is chairing the celebration for the fifth year. Activities continue at Jameson Field behind the fire station with a “family muster’’ competition, including a bucket brigade, a midnight alarm dress, and tug of war. Registration for the muster begins at 1:30 p.m. and the competition begins at 2. And residents will have a chance to take a short ride through town on a firetruck leaving from the station beginning at 4:30. The Sherborn Fire and Rescue Association, made up of firefighters and their families, offers all the activities free of charge as a way of “giving back some of the respect to the community that it gives to us,” Knapp said.