|Morrison sniffing the snow.|
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 materials outlined below.
On National Geographic's Education page there are two resources worth noting. The first is a simple illustration of the position of Earth relative to the sun throughout the year. That illustration could support your use of 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. Both resources are appropriate for elementary school students.
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.