Nets for rectangular prisms
Y6 (10/2010) | ||
a) | Not selected | very easy |
b) | Not selected | easy |
c) | Selected | easy |
d) | Not selected | very easy |
e) | Selected | easy |
f) | Circled | easy |
g) | Not selected | moderate |
a) - g) |
All 7 correct 6 or more correct* 5 or more correct* 4 or more correct** 3 or more correct** |
difficult moderate easy very easy very easy |
Based on a representative sample of 201 Y6 students.
NOTE:
* Students who get 6 nets correct have a slightly higher mean ability than those getting 5 correct.
** Students who get 4 nets correct have a slightly higher mean ability than those getting 3 correct.
There is an even chance of a student getting an individual component correct, so they need to get at least 3 correct to indicate they are not guessing.
fold to make a rectangular prism
Common response | Likely misconception | |
a) or d) | Selected |
Does not see that the prisms have six sides Most students (77%) correctly answered that neither a) nor d) can be folded to make a rectangular prism. |
g) [or b)] c), e) or f) |
Selected Not selected |
Does not visualise more complex nets Students found g) the most difficult, with 13% getting all the other parts correct except this one. |
These students could be asked to count the number of faces on the drawing of rectangular prisms. There are three visible faces, and three hidden faces.
- If they reply that there are six faces, challenge them to explain how many sides a net will need to make a rectangular prism.
- If they cannot correctly visualise the number of faces, get them to do it on actual rectangular prisms. A dice is useful here, because the faces are already numbered.
Also, ask these students what happens to the right-hand part of each of shapes a) and d) when the shape is folded. They should visualise that it is longer than the corresponding sides that it touches. If they cannot see this, get them to cut out the shapes and to fold them.
Does not visualise more complex nets
For students who identified some (but not all the shapes) that can be folded into rectangular prisms, get them working together in small groups. Ask them how many shapes they (as a group) think there are that can fold into rectangular prisms. Get them to justify how each can or cannot fold. If appropriate, let them know there are three shapes that can fold. Get students to design several similar nets and have them ask the group to identify whether they can or cannot fold into rectangular prisms. For groups who cannot reach a (correct) consensus, get them to talk with a group who has. If this fails, get them to work with concrete materials by cutting out and trying to fold the shapes to make prisms (you may wish to enlarge the nets using a photocopier).