Lesson plan for Food Chains and Food Webs , Reflections on the Teaching of Food Chains and Food We

This week, I taught the food chain and food web, and I first gave the students a paragraph describing "the praying mantis catches the cicada and the yellow finch is behind", and asked what idiom this **animation describes? Follow-up question: What is the food relationship between the creatures in Oak Town?

Students can come out: yellow finches eat praying mantises, and praying mantis eat cicadas. When continuing to ask:

What do cicadas eat? Who eats the yellow finches? Some students can eat trees with cicadas, and yellow finches are eaten by eagles.

I directly used arrows to express the food relationship between tree sap --- cicadas--- praying mantises--- yellow finches --- eagles, and asked students to analyze the meaning of arrows. In this session, students can use arrows to indicate who eats who or the relationship between eating and being eaten, but they cannot succinctly state that the arrows point to indicate who is being eaten by whom. I asked:

Why do they eat food? Student: To survive, to get nutrients.

I summarize the students' direct conclusion that they eat food to get nutrients from food, to get energy, to survive. I ask the students to think about what does the arrow mean.

The students are still the same as before. Eventually, I directly told the students that the arrow was pointing to indicate both the relationship between who was eaten and the direction in which the energy flowed. I don't think I should draw an arrow directly in this session and ask students to think about the meaning of the arrow, but should directly ask a question

After explaining the food chain and finding the food relationships of the creatures in the flowers, it was found that these food relationships all started with green plants. Then ask the question: Can the front of the plant's beam increase the number of organisms?

What kind of creature is it the food it inspires? Most of the students were able to increase the number of organisms, for example, pitcher plants can "eat mosquitoes" and Venus flytraps can eat "flies".

At this time, I discovered the students' knowledge misunderstandings, and explained in time that Nepenthes and Venus flytraps only trap and kill mosquitoes and flies, and the plants themselves do not directly digest organisms to obtain nutrients and energy, so the above two examples are not evidence that plants can eat living things.

The lesson "Food Chains and Food Webs" is the fifth lesson of Unit 1 of the second volume of the fifth grade textbook. After this class, I found that it is necessary to practice, consolidate and correct mistakes in time. When students understand the meaning of the arrows ("who is eaten by whom" and "the direction in which energy flows"), they can write a food chain under the guidance of the teacher.

If the range of animals and plants is expanded, and students are asked to mark the arrows according to the relationship between food, there will be students who will mark the arrows in the opposite direction, so it is necessary to have students mark the arrows of the food chain in the book and ask students to mark the arrows on the blackboard, and repeated practice and emphasis can play a role in strengthening and correcting.

In addition, I introduced that the food chain starts with a plant or a part of a plant. In order to test students' mastery, I left an assignment at the end of the lesson and asked students to write down the food relationships (food chains) contained in the sentence "The praying mantis catches the cicada, and the yellow finch comes last".

1. The food chain is a single-chain structure linked by "eating" and "being eaten", and it is not simply eating and being eaten. The food chain is predatory food chain, saprophytic food chain, parasitic food chain, mixed food chain. The structure of the intertwined food chain into a network is the food web.

2. How to establish the concepts of food chain and food web among students is the focus of this lesson, and the basis for establishing the concept of food chain and food web lies in the existence of food relations between organisms, that is, "who eats whom, who is eaten by whom". Clarifying the relationship between eating and being eaten is essential to connect the food chain and form a food web. Through pedagogical activities, it is clear that both producers and consumers are included in the entire food chain.

At the same time, in the teaching of this lesson, students will further experience the relationship between organisms and the environment, understand that organisms are interdependent, interactive and mutually restrictive, especially realize that one animal or plant may be the conditions on which the survival of another animal or plant depends, and then establish a preliminary concept of ecosystem in students' minds, and form the concept that organisms are interrelated.