- Details
- Written by Deirdre Jennings
- Parent Category: Science
- Category: Science 12-15
- Created: 12 February 2011

*PART 2** (find PART 1 **HERE**)*

**STEP 1 - STEP 2:**

Now they have to find a new way to solve the same grouping. We need to learn a new way. This is where we stopped the lesson although some were starting to have the idea of dividing the numbers... We will resume this task tomorrow.

** The idea here is to go through a few more cycles using the same task:** i.e. Allow them to divide the numbers and find proportionalities (body:head) adults 7:1 children 4:1 or 5:1 then relate this to fractions if possible. Then disallow this as a solution. Next solution should be drawing pictures/diagrams showing a child as 4 heads or 5 heads tall and an adult as 7 or 8 heads tall. Then take that away and lead them to graphing (body length vs head length) and finding slopes/gradients. Hopefully this should mean that they have a really solid appreciation of proportion before we go to the graph stage.

**NEXT DOUBLE LESSON: **First we reviewed the previous lessons work as some will have forgotten the point we reached 4 days ago.

**STEP 2 - 1 - 2 again:** Students were very confident in the use of the language 'X length/size compared to length/size of Y' so I said "language - X compared to Y - is now not allowed, find a new way to express the relationship you observed". As this was the first run through I eventually suggested using pictures/diagrams to explain instead of words. No students had started independently making measurements on the pictures yet which was interesting.

After this I said "ok find a new way, not a diagram and not using words". Students did get stuck at this point again, so I sent them back again to the pictures and to review their other descriptions. As a hint I dropped rulers on the tables... They started measuring and after a little while they started dividing the numbers together. They therefore observed that if they focused on one pair of variables that the 'answers' from dividing the 2 numbers were very different for adults than for young animals. They therefore understood that they could USE these numbers to select members of groups. We discussed this and I allowed them to re-sort the 'young' vs 'adult' groups using the various forms of expressions. They observed that these worked smoothly.

Students came up with several different ways/diagrams etc. that worked. See them *H*** ERE**.

**STEP 3: TEST and REFLECT: Challenge after task has reached this stage just before progressing to graphs (as an extension).** Students are asked to organise 5 human skeletons into order of ages. Youngest to oldest or reverse doesn't matter. BUT they must have the calculations done to defend their choice.

This also worked well.