On National Geographic's Education page you will find this hands-on activity designed to help students understand the changes in intensity and duration of sunlight on their part of the world throughout the year. This is an activity appropriate for elementary school students.
Mechanism Of The Seasons is a six minute video about why the length of daylight we receive in a location changes throughout the year. This video could be helpful in a flipped classroom environment as it covers the same information that your students will review in the National Geographic lesson featured above.
Sixty Symbols offers an eleven minute video about equinoxes and solstices. It's not a video that most kids will find engaging, but I'm including it because in it you can see a demonstration of how you can use the free Stellarium software in your lessons.
Although it is not about the winter solstice, Why the Full Moon Is Better In Winter is a good companion resource to go with those featured above.