I recently rattled off a number of tips for my son, who was baking some chocolate chip bar cookies, so I thought I’d share in case anyone reading this is new to baking.

He was reading a recipe for a 10 x 15 jelly roll pan. I have never owned one of those, and I bet none of my friends has, either. Put the dough in a 9 x 13 pan, I told him, and add 5 minutes to the baking time.

How will he know whether they’re done? I told him to try these tests, in order:

• Does the dough jiggle when he starts to slide the pan or rack out?
• If it seems solid, give it a little pressure with a finger. Is there resistance? Or does it make him nervous? Go with your gut.
• If he took it out of the oven because it seemed done, give it a final test with a toothpick or a knife blade. Does it come out clean?

Now that we’ve addressed doneness, let’s jump backward, because that’s what we did here at home.

He was ready to jump into mixing, but all the ingredients weren’t out, and the oven was cold.

Not the best approach, I said. Remember, baking is much more like chemistry than cooking is, and there’s less room for error.

So I told him to do these things right away:

• Preheat the oven.
• Get out the stick butter (actually margarine) and eggs, because you want both to be room temperature.
• To speed the butter-warming process, put the sticks on top of the oven. They will take advantage of both the ambient heat from the warming metal and whatever warm air vents from the oven. BUT if you’re not going to be paying close attention, put them on a saucer so you don’t end up with melted butter all over your stovetop.

Finally, he asked me about baking powder. It turns out the recipe does not call for baking powder, but baking soda, and he knows they are not interchangeable. (Got that? NOT.) He just wondered what baking powder does, and I replied in the most technical terms, that it makes cookies “poofy.”

Your takeaway from this? Ingredients expire. Just like spices, just like makeup – sorry if these are shocking revelations – baking powder and baking soda both have expiration dates that should be honored, because freshness makes a difference in your end product.

I told my son that I had made sure to buy new containers of both for Christmas baking. If yours are out of date, spend the less than $2 to get new ones so your baked goods rise properly. It’s a worthwhile investment.

Did I miss a basic baking tip? Have a horror story to share? I love comments, don’t be shy.