# WitCH 137: Holey Cow

OK, this is the final one (unless someone provides me access to more tests). This last one is from the calculator part of the 2021 Year 7 test. A reminder that all the NAPLAN WitCHes, and the other NAPLAN posts, can be accessed here. Tomorrow(ish), I will write on NAPLAN post-2021.

## 8 Replies to “WitCH 137: Holey Cow”

1. Potii says:

Options one and two are both valid answers. I was able to achieve the required cut pattern and use only three folds (all along the lines of symmetry) with option two.

1. marty says:

Presumably they would argue that option 2 has already included one unfolding.

1. Potii says:

I did it without unfolding.

1. Fold in half so that the fold is perpendicular to a pair of sides.
2. Take the one of the corners that is along this fold and push it inwards towards the mid point of the diagonally opposite side to do a reverse-inside fold (this can be done without any prior preparatory folds if you are very careful).
3. Repeat 2 for opposite corner.

3 folds. Though I’m not sure if they would be happy with a reverse-inside fold but all I did was take a corner and crease the paper once. It is a bit tricky getting the midpoint accurate to make the folds symmetrical but it is posible.

1. marty says:

That’s very funny (and clever). Thanks, Potii.

2. Ron says:

I think I mustn’t be following (or understanding) your directions correctly, Potii. I’m unclear on what the “diagonally opposite side” is.
When I (probably mis-)follow your directions I end up with a triangle which looks like option B, but if I unfold this triangle there are only 3 of the four lines of symmetry creased into the paper (horizontal and two diagonal).
What am I missing?

1. Potii says:

Ahh you are correct, I missed out on one line for symmetry. Well I guess I wasn’t that clever after all.

2. Terry Mills says:

I wonder how many Year 7 students would understand the meaning of “lines of symmetry”.

I was in a cafe sometime ago, and nearby were two mothers and their daughters. One mother said to the other that she always helps her daughter with her homework. The daughter piped up “You didn’t last week”. Mother “What do you mean? I always help.” Daughter said “You didn’t. You could not tell me what ‘symmetry’ means.” Mother, “Well, who uses word like that?”

1. marty says:

I don’t even understand why “symmetry” is there.