Using (or not) the word "to" in a sentence ending with "be able"

Which of these is grammatically correct?

• As educators, we are always looking for ways to reach all the learners in our classroom as effectively as we are able.

• As educators, we are always looking for ways to reach all the learners in our classroom as effectively as we are able to.

Solution 1:

Just a made up rule, created by a 17th century poet called John Dryden and later popularized by an 18th century clergyman called Robert Lowth.

There's nothing wrong with ending sentences with prepositions. English is part of the germanic rooted languages and being so, it shares the ways sentences are written. So, it's ok.

What's not ok is over-using them. Here's an example and you can check also more great Q&A's: http://www.grammarphobia.com/qa#a1

OK, didn´t want to copy&paste but I think some people is too lazy to check and read:

1. Preposition at the end:

There’s no grammatical reason not to end a sentence with a preposition. The 17th-century poet John Dryden concocted this so-called rule, apparently to make English act more like Latin. But we can blame Robert Lowth, an 18th-century clergyman and Latin scholar, for popularizing it.

The prohibition caught on, perhaps because of its simple-mindedness, even though great literature from Chaucer to Shakespeare to Milton is full of sentences ending in prepositions (positioning words like “at,” “on,” “over,” “up,” and so on).

The reason we’re compelled to end sentences with prepositions is that this is a normal Germanic sentence structure. And English is a Germanic (not a Romance) language. (See FAQ #33.)

While there’s nothing wrong with ending an English sentence with a preposition, one can overdo it. A quotation, attributed to E. B. White, shows how silly a pile of prepositions can sound. Child supposedly says to father, who has brought the wrong book upstairs for bedtime reading: “What did you bring me that book I don’t want to be read to out of up for?”

2. Split infinitive:

The belief that it’s wrong to split an infinitive is a notorious myth that grammarians have been trying to debunk for generations. This never was a genuine rule. It was merely a misconception based on the wrong-headed notion that English (a Germanic language) should conform to the rules of Latin sentence structure.

An infinitive is a verb in its simplest form and often has the word “to” in front of it: “Darcy helped to find Lydia and Wickham.” But the “to” isn’t actually part of the infinitive and it isn’t always necessary: “Darcy helped find Lydia and Wickham.”

The myth against “splitting” an infinitive was born in the 19th century when Latin scholars misguidedly called it a crime to put a descriptive word between the prepositional marker “to” and the infinitive: “Darcy helped to quickly find Lydia and Wickham.”

Since “to” isn’t part of the infinitive, however, nothing is being split, and the whole idea of “splitting” an infinitive is nonsense. (In Latin, the infinitive is a single word without a prepositional marker, and obviously can’t be split.)

A sentence often sounds better when the “to” is close to the infinitive, but there’s no harm in separating them by putting an adverb or two in between. Writers of English have been happily “splitting” infinitives since the 1300s. So if you want to happily join them, feel free.