Multi-Digit Multiplication Strategy: Doubling/Halving Factor(s)

Two things...

First:
Take a deep breath.

Second:
Keep this in mind:  
This strategy should be used on a "case-by-case" basis, depending on the factors.  
It should be used to make an easier, simpler problem when possible.

Here we go...

 This strategy is only useful when both factors are even or if one factor is odd and the other is even since you can't halve an odd number without using fractions.

Since both odd an even numbers can always be doubled, this strategy is useful in more contexts.  It's especially useful in this context, when multiplying by 5.  Some students struggle more with halving numbers, so this strategy may be more challenging for those students.

Bottom Line: Yes, this strategy will get you the correct answer.  Yes, it is neat to see that doubling one factor and halving the other will result in an equivalent problem.  No, it is not efficient, which will lead us into using a traditional algorithm next week.  :-)