張軍霞

我們倡導(dǎo)要提高課堂教學(xué)的有效性，實現(xiàn)學(xué)生課堂教學(xué)的真正獲得。對于科學(xué)課堂教學(xué)，我們可以從微觀層面上組織課堂教學(xué)的具體內(nèi)容，厘清課堂教學(xué)的主線。對于教學(xué)目標(biāo)中包含課程標(biāo)準(zhǔn)要求的某一學(xué)習(xí)目標(biāo)的科學(xué)課堂來說，可以按照學(xué)生理解這一學(xué)習(xí)目標(biāo)的由淺入深的發(fā)展路徑組織學(xué)習(xí)內(nèi)容，實現(xiàn)一堂課的概念進(jìn)階。課程標(biāo)準(zhǔn)中的各水平級學(xué)習(xí)目標(biāo)，可以理解為由某一主要概念分解的水平級概念。在40分鐘的課堂上理解一個水平級概念，可以參考《基于核心素養(yǎng)學(xué)習(xí)進(jìn)階的科學(xué)教學(xué)設(shè)計》一文中用于較短時間內(nèi)具體科學(xué)概念的學(xué)習(xí)進(jìn)階的“科學(xué)概念理解的發(fā)展層級模型”（以下簡稱層級模型）進(jìn)行設(shè)計。

層級模型將對概念理解的發(fā)展路徑分為經(jīng)驗、映射、關(guān)聯(lián)、系統(tǒng)和整合五個層級。這五個層級的概念理解程度可以這樣理解：經(jīng)驗，學(xué)生具有一些沒有產(chǎn)生相互關(guān)聯(lián)的日常經(jīng)驗和零散事實；映射，學(xué)生能夠建立概念與經(jīng)驗之間的關(guān)系；關(guān)聯(lián)，學(xué)生能夠建立概念與多個經(jīng)驗特征之間的關(guān)系；系統(tǒng)，學(xué)生能夠建構(gòu)對科學(xué)概念的基本理解；整合，學(xué)生能夠在更廣泛的情境中應(yīng)用概念，表現(xiàn)出具有一定的科學(xué)觀念，或跨學(xué)科解決問題的能力。

例如，二年級《把它們放進(jìn)水里》一課，設(shè)定的重點教學(xué)目標(biāo)對應(yīng)課程標(biāo)準(zhǔn)中的1～2年級學(xué)習(xí)目標(biāo)：知道有些物體能夠溶解在一定量的水中，如食鹽和白糖等；有些物質(zhì)很難溶解在水里，如沙和食用油等。按照層級模型的發(fā)展路徑開展教學(xué)，能夠使學(xué)生在一堂課中初步建構(gòu)這一概念。

經(jīng)驗：出示白砂糖、酸梅晶（或紅糖）、木屑、沙子等一些易溶解和難溶解的固體物質(zhì)，讓學(xué)生預(yù)測這些物質(zhì)放入水中會怎樣，獲得學(xué)生對溶解的原有認(rèn)識。

映射：將這些固體物質(zhì)放入水中，獲得對溶解的最初認(rèn)識——固體看不見了。

關(guān)聯(lián)：將酸梅晶放入水中，觀察酸梅晶放入水中的過程，獲得對溶解的初步認(rèn)識——固體均勻分散在水中。將食用油、蜂蜜等液體物質(zhì)放入水中，獲得對溶解的初步認(rèn)識：液體也能均勻分散在水中。

系統(tǒng)：通過對上述現(xiàn)象的歸納，初步概括什么是溶解——物質(zhì)均勻分散在水中，看不見了。

整合：在本節(jié)課即將結(jié)束之時，將許多鹽倒入少量水中，獲得指向主要概念的科學(xué)認(rèn)識——物質(zhì)在水中溶解的量受到水量的限制，即物質(zhì)溶解在一定量的水里。

如果教學(xué)目標(biāo)包含的科學(xué)概念有多重含義，在應(yīng)用層級模型進(jìn)行教學(xué)設(shè)計時，五個層級可以交錯進(jìn)行。

例如，三年級《食物的消化》一課，設(shè)定的重點教學(xué)目標(biāo)對應(yīng)課程標(biāo)準(zhǔn)中的3～4年級學(xué)習(xí)目標(biāo)：簡要描述人體用于攝取養(yǎng)分的器官。本課教學(xué)對消化器官的認(rèn)識，要與食物進(jìn)入人體被消化的路徑結(jié)合起來。

經(jīng)驗1：在口腔里咀嚼饅頭，體會咀嚼過的饅頭在牙齒、舌頭、唾液作用下，變小了、黏了、甜了。

映射1：用碘酒檢查咀嚼過和沒有咀嚼過的饅頭，體會饅頭的初步消化——部分淀粉變?yōu)樘恰?/p>

關(guān)聯(lián)：吃入冰鎮(zhèn)的水果，體會食物由口腔進(jìn)入消化器官的上部路徑——食物從口腔經(jīng)食道進(jìn)入胃。

經(jīng)驗2：畫食物路徑圖，了解學(xué)生對消化器官的已有認(rèn)知。

映射2：觀察消化器官立體圖，初步認(rèn)識消化器官。

系統(tǒng)：觀看介紹消化器官的視頻資料，綜合以上教學(xué)經(jīng)驗，學(xué)生可以認(rèn)識食物在經(jīng)過消化器官的過程中逐漸被消化、吸收的基本過程。

整合：如果還有教學(xué)時間，本課最后可以引導(dǎo)學(xué)生學(xué)習(xí)如何保護(hù)消化器官。

以上探討的都是以建構(gòu)科學(xué)概念為重點教學(xué)目標(biāo)的課例。不以建構(gòu)科學(xué)概念為主的其他科學(xué)課堂，如屬于技術(shù)與工程領(lǐng)域的設(shè)計、制作、評估、改進(jìn)等課，需要結(jié)合設(shè)計思維與工程思維設(shè)計教學(xué)。

Strive to Realize the Concept Advancement of a Class

ZHANG Junxia

中圖分類號：G424文獻(xiàn)標(biāo)識碼：ADOI：10.16400/j.cnki.kjdk.2021.05.001

ZHANG Junxia

Deputy Director （in charge of work） and Editor of Comprehensive Science Department of People’s Education Press

Member of the Textbook Compilation Group of Science Published by People’s Education Hubei Education Press

Deputy Secretary General of Science Popularization Education Committee of China Science Popularization Writers Association

We advocate improving the effectiveness of class？ room teaching and realizing the real acquisition of students’ classroomteaching. For scienceclassroom teaching，wecanorganizethespecificcontentof classroom teaching from the micro level and clarify the main line of classroom teaching. For the science classroom whose teaching objectives include a certain learning objective required by the curriculumstan？ dard， we can organize the learning content according to the development path of students’ understanding of this learning objective， and realize the concept ad？ vancement of a class. The learning objectives of each level in the curriculum standard can be understood as the level concept decomposed by a main concept. Tounderstandalevelconceptinthe40-minute class， we can refer to the "hierarchical model for the developmentofscientificconceptunderstanding"（hereinafter referred to as the hierarchical model） in the article "advanced science teaching design based oncoreliteracylearning"，whichisusedforthe learning of specific scientific concepts in a short time.

The hierarchical model divides the development path of concept understanding into five levels： experi？ ence，mapping，relevance，systemandintegration. These five levels of conceptual understanding can be understood as follows： experience， students have some daily experience and scattered facts that are not relat？ ed to each other； Mapping， students can establish the relationshipbetweenconceptandexperience；Rele？ vance， students can establish the relationship between concepts and multiple experience characteristics； Sys？ tem， students can construct the basic understanding ofscientificconcepts；Throughintegration，students can apply concepts in a wider range of situations and show a certain scientific concept or interdisciplin？ ary problem-solving ability.

For example， in the second grade lesson "put them in the water"， the key teaching objectives set correspond to the learning objectives of grade 1-2 in the curriculum standard： know that some objects can be dissolved in a certain amount of water， such as salt and sugar， etc； Some substances are difficult to dissolve in water， such as sand and edible oil. Ac？ cording to the development path of hierarchical mod？ el， students can construct this concept in a class.

Experience： show some soluble and insoluble sol？ id substances， such as white granulated sugar， sour plum crystal （or brown sugar）， sawdust， sand， etc.， andaskstudentstopredicthowthesesubstances will be put into water， so as to obtain students’ origi？ nal understanding of dissolution.

Mapping： put these solids in water to get the first idea of dissolution - the solids are out of sight.

Relevance： put sour plum crystal into water， ob？ serve the process of putting sour plum crystal into water， and get a preliminary understanding of dissolu？ tion - solid is evenly dispersed in water. Put edible oil， honey and other liquid substances into water to get a preliminary understanding of dissolution： liquid can also be evenly dispersed in water.

System： through the induction of the above phe？ nomena， we can preliminarily summarize what is dis？ solution - the matter is evenly dispersed in water and cannot be seen.

Integration： at the end of this lesson， pour a lot of salt into a small amount of water to get a scientif？ icunderstandingofthemainconceptthatthe amount of matter dissolved in water is limited by the amount of water， that is， matter dissolved in a cer？ tain amount of water.

If the scientific concepts contained in the teach？ ing objectives have multiple meanings， the five levels can be staggered when applying the hierarchical mod？ el to the teaching design.

For example， in the third grade of "food diges？ tion"， the key teaching goal set corresponds to the learning goal of grade 3-4 in the curriculum stan？ dard： briefly describe the organs used by the human body to absorb nutrients. The understanding of diges？ tive organs in this course should be combined with the path of food entering the human body and being digested.

Experience1：chewingsteamedbreadinthe mouth，experiencechewingsteamedbreadinthe teeth， tongue， saliva， smaller， sticky， sweet.

Mapping1：checksteamedbreadchewedand not chewed with iodine wine， and experience the ini？ tial digestionof steamedbread--part of starch turns into sugar.

Relevance： eating iced fruit， experience the up？ per path of food from the mouth to the digestive or？ gans - food from the mouth through the esophagus into the stomach.

Experience 2： draw food path map to understand students’ cognition of digestive organs.

Mapping 2： observe the stereogram of digestive organs to get a preliminary understanding of digestive organs.

System： by watching the video materials about di？ gestive organs and integrating the above teaching ex？ perience， students can understand the basic process that food is gradually digested and absorbed in the process of passing through digestive organs.

Integration： if there is still teaching time， this lesson can guide students to learn how to protect di？ gestive organs.

The above discussion is based on the construc？ tion of scientific concepts as the focus of teaching ob？ jectives. Other science classes that do not focus on the construction of scientific concepts， such as de？ sign， production， evaluation and improvement in the field of technology and engineering， need to combine design thinking with engineering thinking.