when: after breakfast

what materials: Mental Maths 7-8, Test 21

J2: Daddy, what is the correct answer?

J0: What do you think?

J1: I think it is (a) because the circle is 2-dimensional while the cone and the cylinder are 3-d.

J0: What about you, J2?

J2: I think (b) because the cone is the only one with a sharp point.

J0: Hmm. What about the cylinder? is there a reason it could be the odd one out?

<a while for thining>

J1: The circle and the cone are both used to make a pseudosphere (see yesterday!) while the cylinder isn't, so the answer is (c)!

J0: Great idea! So what does it mean to answer this type of question?

.....

# What is your reasoning?

We proceeded to talk about how any of the choices could be an odd one out and that a proper answer to this type of question was at least some identified property in which the odd-one differs from the other two. I emphasized that the best thing you can do is try to come up with as many different ideas as possible and we talked about some:- number of dimensions
- number of vertices, sides, faces
- straight vs curved sides
- number and types of symmetries

# Those Diagrams . . .

One other thing we could have talked about: what is actually being depicted in the three choices? For examples of what these diagrams could be:a) Circle, disc, or solid shape with circular disc base viewed from a perspective that hides teh rest of the shape

b) Cone boundary (with or without the disc at the base), solid cone, or circular segment with another circular arc forming a loop

c) cylinder boundary (with or without discs on the end), solid cylinder, or rounded rectangle with extra curve arc forming a loop

## No comments:

## Post a Comment