How can I teach a $7^\text{th}$ grade student the concept of ratio and proportion

Question

How can I teach a $7^\text{th}$ grade student the concept of ratio and proportion with the use of teaching aids ( such as models or Charts) . One of my friends asked me this question.

One possible solution could be found using of spring of length length 5 units (,say) and a scale (marked with numbers from $1$ to $10$). I colour the spring to the length of 3 units . Then I stretch the whole spring upto $10(= 5 \times 2)$ units and see the coloured portion stretches upto $6 (=3 \times 2)$ units.

Is there any other easier way (of course by using appropriate teaching aids) to grow the concept of ratio and proportion ?

Thanks in advance for your time.

Answer 1

One nice model is mixing paint.

Make a color by mixing one part yellow to two parts red by volume.

Then you can ask questions like:

"If I add one more cup of yellow paint, how much red paint must I add to get the same color?"

"If I double the amount of yellow paint, what will I need to do to the red paint to maintain the same color?"

"If I add one tsp of yellow and one tsp of red paint, will the new color be 'yellower' or 'redder' than the old color"?

Students can actually play with mixing small quantities of paint this way.

Answer 2

I like food math.

Students wanting 2 slices of pizza for lunch. This sets up a 2:1 ratio, pizza:students.

You can then move on to ravioli, at which point the ratio is 6:1 for medium ravioli.

The next step is a recipe in which you have butter, eggs, sugar, flour, in a given ratio and you can change the number of results (the cookies/muffins/etc) and ask for how much of each ingredient is needed.

The above started with my daughter nearly a decade ago. We were making brown rice and had a 'recipe' that was 4 cups water, 2 cups rice. When she measured the rice and saw only 1-1/2 cups, I said "I guess we can't make rice for dinner." She showed her knowledge of ratios, and said we'll just use 3 cups of water. Not bad for a 7 year old.

Answer 3

In order to achieve a deeper understanding of what ratio and proportion are, you can use short fragments from Peppa Pig's 4x02 episode, The new house. Peppa's dad works as an architect and he designs a new house for his neighbours, the Wolf family. He gives his drawing, which can be seen in an explicit way, to the construction workers. Then, they build the house.

After watching these fragments, you can think of a similar activity. Make your students to draw a design (with just straight lines and so) in their notebooks. Just to finish, tell them to build it with construction blocks.