When you're home, experiment based science is going to be your best friend. There are lots of easy ones you can do with basic ingredients. The important thing is to get the kids to make observations and then write and draw what they observed. I've included some links for experiments we loved.
Clean a Penny with Chemistry Make sure you have a lot of pennies on hand. I made sure to have one that were in different states of dirty so they could see how dramatic the change was for the dirtiest.
Alka Seltzer and Oil Lava Lamp My kids loved this one like crazy. Experiment with how different amounts of alka seltzer tabs to see the changes!
Melting Ice This is beautiful and made entirely with ordinary kitchen items. If you don't have time to make a big block of ice, either use ice cubes or, y'know, get some ice from outside your front door. I bet an icicle would be phenomenal for this experiment!
Frozen Bubbles I can't think of better weather to try this one! If you have to go out, might as well do some science while you're out there!
Inflate a Balloon with Science We enjoyed this one a lot. All you need is a balloon, an empty bottle, vinegar and baking soda!
Another important thing to do is work on various elements of language arts. Here are a few ideas to help with that!
Composition This link will send you to some writing prompts, but you could just as easily invite your kids to freestyle and simply compose a story. You can also challenge them to write a rhyming poem.
Spelling A great follow up to composition is to identify any spelling problems they encountered. Make a list of all the improperly spelled words and get them to write them correctly about 10 times. This will help them remember the correct spelling for the future!
Word Searches This is just an example of the types of word searches you can find if you go and search them on the internet. Print out a few at a time and set them searching.
Handwriting For younger kids, practicing letters and handwriting is always a good idea. Set them down with a piece of loose leaf and ask them to write each letter 10 times. When they're done, identify letters they had problems with and spend time helping them write them correctly.
Work Sheets Find some work sheets for your child's age and grade. Let them do the worksheet alone and then come and check over their work. This will help you identify and help with any problem areas.
Word Problems Just like the other work sheets, print out some with word problems as this will get them thinking in a whole new way.
Art: Google a famous painter and learn a little bit about them. Find out what was special about their style and then see if you the kids can mimic something about their work. You can also do a project where you show how mathematical shapes can be used to form the basic shape of any object.
Geography: Pick a country and ask them to do a mini research project. Population, language, cultural dance, food, music, and history are all fun points to touch on. Consider setting them a list of questions to look for.
Baking and Cooking: Let the kids cook with you. Explain why the flavours work together, what culture the food comes from and what is nutritious about the food choices.
Play: Don't forget to have fun! If you're snowed in, try making some of the many home made doughs for some sensory play. I love adding some peppermint extract to make even the most basic dough fun! This no bake recipe was incredibly popular with my kids and help up nicely next to the name brand stuff.
I hope these ideas inspire you and help you through these long snowy days!