Not just cleaning up the crumbs after using a cutting board (keep a sanitized towel nearby to clean it quickly and it'll turn into something). Different ingredients are needed to make a dish. The quality of the ingredients you use can make it a success or a failure. This may sound like a fad, but you should know that the success of a dish depends mainly on the ingredients used.
You can't prepare a fresh fish dish with an old fish no matter how fresh the spices are; even the best chef in the world will have a hard time doing it. The best way to make sure you're using the freshest ingredients is to get them the day you need them. If you don't have time to visit the market on a daily basis, refrigerating them can also work as long as you consume them within the next 24 hours. If you're used to freezing meat and seafood, try using freezer bags to retain freshness and prevent burns.
Of course, fresh foods are still better compared to frozen foods. For groups that will help you cook, consider buying supplies that are separate from those you normally use in the kitchen. This way, you don't have to worry about a customer ruining your favorite chef's knife or piano whip. When the event is over, you can wash everything and store it in an area just for cooking class materials.
Aprons, mixing bowls, additional chef knives, and cutting boards are some basic food preparation items that can help cooking classes at your restaurant. You can also provide printed recipes so that customers can take notes and remember what they helped you prepare. Experienced chefs can determine if a chicken breast is perfectly cooked solely based on its appearance, but many cooks find it useful to rely on a meat thermometer. On many YouTube cooking channels, I've learned that many of the old school teachings about cooking and baking don't apply.
Knowledge of cooking techniques allows you to work with a variety of ingredients and kitchen equipment to achieve consistent and tasty results in your kitchen. So stop trying to cut those onions with a blunt knife and invest in some good quality kitchen utensils, as not only will they save you a lot of time (and tears), but they'll make a big difference in your cooking skills.