One way to turn the average shopping trip into a fun learning experience is to play I Spy:
For younger kids this can be as simple as asking them to identify basic shapes, colors, letters and numbers in whatever aisle you are in. For example, you could say, "I spy something that is red." Your child will look for something red such as an apple or spaghetti sauce. Or, "I spy the letter 'A'." Your child will look at packaging and price tags in search of the letter 'A.' Older kids can look for goods that contain certain ingredients or are popular in certain cultures or geographical locations. For example, "I spy a food that is popular in Mexico." Your child will look for foods that are popular in Mexico such as tortillas or jalapenos. To incorporate lessons on nutrition, you may have your children look for foods that are protein rich or foods that are high in carbs, etc.
The produce aisle is a great place to talk about seasons, and locally grown food versus imported food. Ask your kids to determine which produce is in season in your area by looking at where the produce is from.
In the cereal aisle you might ask your kids to pick out their favorite cereal box and ask them why they chose it. What do they like about it? Is it the colors on the box? The cartoon character that endorses the brand? This is a good way to provoke thinking about marketing and raise savvy consumers.
For a finance lesson, you can give your kids a budget and ask them to find as many items on your list as possible without going over budget. This will encourage price comparisons and addition/subtraction skills. And the checkout line is a good place for money counting if you are paying with cash.
These are just a few ideas to get the ball rolling. I'm sure once you start to think about it you'll come up with even more ways to turn your ordinary grocery trip into a learning adventure. Happy shopping!