Sabrina: Hey there, future engineers! Welcome back! We ended our last engineering lesson, which was all about coming up with multiple solutions to a single problem, on a bit of a cliffhanger. So let's jump back in and see if we can answer the question we asked at the end of that lesson: Is one solution even better than another?

S: Let's do a quick recap. You remember that an engineer is a person who designs and builds things to solve specific problems. The process they follow when they're doing this is called the engineering process, or a series of steps that engineers use to guide them as they work toward a solution for whatever that particular problem is. Scratch that; not "solution" singular, "solutions" plural.

Real engineers always brainstorm more than one solution to a single problem. This way if one possible solution doesn't work, they always have more options to test.

So how do engineers figure out which solution is the best solution? Well engineers put a lot of thought into deciding which might work best for their problem. They look at each of the solutions they brainstormed in a logical or reasonable way, and ask questions about each option. Think of it sort of like making a list of pros and cons, or strengths and weaknesses, for each possibility. Ready to try thinking like an engineer? Cool. Let's do this.

S: We'll examine all three of the possible solutions we came up with last time to our gorge problem and see if we can figure out which one is the best solution.

First up is our Up solution, building a balloon-powered air lift. Let's take a look at the solution's strengths first. Does it meet our original requirements for being a good solution? Well, it sort of meets requirement two since it involves some materials we already have, namely balloons. But it also requires materials we don't have, like a helium tank.

I mean, we can't blow up the balloons with our own lung power and expect them to lift us across the gorge. In order for the balloons to float up, they need to be filled with helium gas, or maybe really hot air like in a hot air balloon. And we don't have either of those.

As for requirement three, we should be able to use them as balloons again on the other side if we want to, so that's something.

But what about requirement number one, remember the one about getting us to the other side alive? Well as an engineer, it's important to think big and sometimes that involves crazy ideas that people would never thought possible, like space ships or computers. There's nothing wrong with thinking like that, and you totally should think like that during the engineering process. But sometimes you have to be logical and know when an idea is too crazy, and in this case unsafe. And I'm sorry to break it to you guys, but one pack of balloons filled with regular old air- no matter how big you blow them up- won't get us to the other side of the gorge alive.

A real engineer would test this on solid ground and come to the same conclusion. But that's okay, we have two other solutions to look at.

Our next solution is our Mary Poppins style solution: floating over the gorge with our umbrella. Like our first solution, this involves materials we have- an umbrella- and we'd be able to reuse the umbrella again on the other side of the gorge if we needed to.

But what about our other stuff? If we're using one hand to hold our umbrella, we'll only have one hand free to carry our other stuff, like our tent. And that stuff would probably weigh us down as we try to float across the gorge. So once again, we need to ask, will this solution get us to the other side alive? Sorry again, but I'm thinking no. Our umbrella is not very big and this gorge is. Even if we get a good running start, if we leap off this gorge, we won't float all the way across with our small umbrella. Plus we'd probably have to leave our other stuff behind. After all, Mary Poppins was make-believe, not real, so pretend solutions won't work for real engineers. 

And just like in the first solution, if engineers were to test this, they'd find that they couldn't get afloat with an umbrella. But fear not brave engineers, our final solution awaits!

To hang glide or not to hang glide? Okay requirement number two. We can try this solution with the materials we already have, our tent. Requirement number three, we can disassemble the glider on the other side and reuse it as a tent. Bonus, we'll have to carry less of our stuff across the gorge because some of it will already be on our back. Time for the big question: will we get across alive?

A good engineer with a good sturdy tent and the knowledge of how to build a working hang-glider might just be able to create something that would get them to the other side. But they would test this solution many, many, many, many times before they actually let me or some other person try it for real. Did I mention that they would test it many times? And if for some reason the hang glider didn't work, the engineer would go back to the drawing board and come up with even more possible solutions.

So as cool as it might be to float across a gorge by a bunch of balloons or holding on to an umbrella, the hang glider option seems to have more strengths and fewer weaknesses than the other two. And even though the hang glider might not end up being the winning solution to this problem, it's the best of the options we have now.

S: Which means-drum roll please- yup, some solutions are better than others. By thinking logically, asking questions, and looking at potential solutions strengths and weaknesses, you can determine which solution is the best solution to a problem. Happy engineering!