The great thing about preschoolers is that they learn through play. You don’t have to knock yourself out trying to teach them, but talk to them, read to them, and let them be active.
If it’s still cold where you live, go out to play in the snow. Build a snowman, throw snowballs. Mix different food colorings into spray bottles so they can color the snow (you can talk about yellow + red = orange, red + blue + purple, etc). Set up a bird feeder and talk about the birds that come to eat. Better yet, have the kids collect pine cones, smear them with peanut butter, and roll them in bird seed. Hang these up and watch for birds. Go on a “nature walk” and collect rocks, sticks, and leaves. Have the kids sort them into piles (early math skills) and talk about the different textures and colors of the materials.
In the summer, plant a small garden or even just some sunflowers in pots. Grow flowers. Collect bugs, play with water, color with sidewalk chalk. The best thing you can do for the kids is to get right down on their level and play with them. Be open to their ideas, use a lot of imagination and encourage them to pretend. Blow bubbles, take a walk, play in the sand.
Inside, preschoolers can benefit from having a short “circle time” each day. Read a picture book, talk about the date and the weather. Afterward, do a craft that ties into the book or some other theme you’ve been discussing. Try to remember that the process of the craft is far more important than the product. That means give them the art materials and let them use them in whatever way they want without being destructive, of course without focusing on what the end result of the craft will be. Display these crafts in places where the children can see them and talk about them. Sing along and dance to music.
Let the kids use play-doh, blocks, Legos, dolls, musical instruments, a play kitchen, a doctor kit, and dress-up clothes. Make sure the day is balanced between activities planned and guided by you, and “free play” where the children choose what to play with and how to play with it.
Visit your local library and check out some books about games and activities for kids. You will find literally hundreds, if not thousands, of ideas for games and crafts using household items or things found in nature.
Read. Read a lot. Then read some more. Hug them a lot, laugh a lot, and have fun!