How many dollars?: a mathematical inquiry

Walter’s agenda item at a morning meeting several weeks ago has developed into a major project. As a result, the children have been:

The most recent development has been a mathematical inquiry as the children used various materials and strategies to try and work out how much money we will need to buy more fish for our fish tank. We began with a discussion about how many fish and plants we should buy. The children decided that we should have a total of six fish and and six plants. Several children pointed out that since we already have one fish, we would only need to buy five more fish.

I explained to the children that we could estimate the approximate cost of fish and plants based on the information we had gathered from our research. I decided to work in $US rather than Japanese yen, as I thought it would be easier for the children to work with smaller numbers. I estimated that one fish would cost approximately $5 and one plant would cost approximately $3. I wrote the information on the white board so that the children could refer back to it during their inquiry.

I thought about whether I would guide the children’s inquiries at this stage and decided not to give them suggestions, and instead to observe the ideas and strategies the children came up with.

Some children chose to work by themselves and others sought out partners. Although there was a wide range in the level of the children’s mathematical understanding, everyone took the work very seriously. Some children selected materials to help them count, others used fingers, and still others went for paper and pencil. Children used pictures, arrows, tables and letters to show their mathematical thinking. They discussed their findings and puzzled over conflicting answers. The video clip below shows the depth of mathematical thinking and, at times, frustration, as two children compare their answers. The look of delight and satisfaction is evident on both children’s faces as they finally solve the problem! It reminded me once again of the importance of giving children time to find out for themselves, rather than giving them the answers.