八年级下册（2024）Cross-curricular connection课前预习课件ppt

这是一份八年级下册（2024）Cross-curricular connection课前预习课件ppt，文件包含四川省泸州市三校联盟2025-2026学年高二上学期第一次联合考试语文试题评讲课件pptx、四川省泸州市三校联盟2025-2026学年高二上学期第一次联合考试语文试题原卷pdf、四川省泸州市三校联盟2025-2026学年高二上学期第一次联合考试语文试题答案与解析pdf等3份试卷配套教学资源，其中试卷共16页， 欢迎下载使用。
Pre-reading
D yu ever g n rad trips with yur family? Hw d yu find yur way? D yu use any map apps? Hw des the app help yu find yur way t the destinatin?
The app shws us where we are. It gives us the fastest way t get t the destinatin, and it als tells us where t drive and when t turn. The app als shws us traffic in real time.
Hw des the app knw where yu are? It uses signals frm satellites in space.
navigatin /ˌnævɪˈɡeɪʃn/ 导航
satellite /ˈsætəlaɪt/ 卫星
Discuss in pairs.
Hw des BDS Wrk? Let’s explre the science behind it!
Hw BDS wrksWhat is BDS?BDS, fficially knwn as the BeiDu Navigatin Satellite System, is ne f the glbal navigatin satellite systems.Hw des BDS wrk? BDS is a grup f satellites in rbit arund the Earth. Each satellite sends radi signals t the Earth with infrmatin. The signals answer tw imprtant questins: “Where in space is the satellite?” and “When did the signal leave the satellite?”The radi signal travels thrugh space at the speed f light—that is 299,792 kilmetres a secnd! Back here n Earth, yur phne receives the signal and cmpares it t the exact time f arrival. The phne then calculates hw far it is frm the satellite.One satellite is nt enugh. Yur phne needs infrmatin frm fur satellites t calculate yur lcatin. It des this all the time. S, when we use a BDS device, we wn’t get lst.What’s special abut BDS?We can als use BDS fr tw-way cmmunicatin. In areas withut any mbile netwrk, peple can send text messages thrugh BeiDu satellites.Hw d we use BDS?If yur phne supprts BDS, it will autmatically pick the navigatin system with the best signal at the time. Can we use BDS utside China? Yes, we can use BDS utside China, but its accuracy is higher in China and the Asia-Pacific regin.
BDS = BeiDu Navigatin Satellite SystemIt is a Glbal Navigatin Satellite System (GNSS).It helps us find ur lcatin anywhere n Earth.
Read the definitin. What des “BDS” stand fr, and what is it? What is it used fr?
While-reading–What is BDS?
Where are the BDS satellites?2. What d the satellites send t the Earth?3. Hw can we receive the BDS signals? 4. Hw many satellites des yur phne need t calculate yur lcatin? 
 They are in rbit arund the Earth.
Radi signals with infrmatin abut their lcatin and time.
We can receive the signals with a phne r ther device that supprts BDS.
Lk at the text and answer the questins.
While-reading–Hw des BDS wrk?
1. What is special abut BDS?
We can use BDS fr tw-way cmmunicatin. In areas withut any mbile netwrk, GPS nly allws yu t receive signals, but peple can bth receive and send text messages thrugh Beidu satellites.
Example: The engine n a ship breaks dwn when a fisherman is ut at sea. There is n mbile netwrk, and the ship’s radi desn’t wrk.With GPS, the fisherman can nly get his lcatin, but he cannt cmmunicate. If he has a special BDS device, he can send an SOS message with his lcatin. He can als receive messages with the BDS device.
2. In what situatins might this feature be useful?
While-reading–The special features f BDS
In grups, discuss hw BDS helps these peple.FarmersTaxi drivers / Delivery driversScientists Pilts / Sailrs Yu (Walking, biking, finding friends, …)
Chse ne r tw f the grups abve. Hw des BDS help them? Hw can BDS help yu? Share yur ideas with the class.
Pst-reading
A timeline: the develpment f BDS
Self-assessment
Each grup chses ne f the fllwing tpics (r anther tpic related t China’s space prgramme).China’s manned space prgrammeChina’s lunar explratin prgramme Lng March rckets seriesTianwen Mars missinTask:Find infrmatin abut the tpic and make a simple timeline abut it. Resurces:Visit English science r news websites.Yu may use AI tls t help yu find infrmatin and rganize yur ideas.
hit v. 碰撞；撞击 The car hit a tree during the strm.
adjust v. 适应；习惯 It tk him a while t adjust t the new schl.
naked eye 肉眼 The planet Mars is very bright and easy t see with the naked eye.
pint n. 时刻；阶段 At that pint, she was t tired t cntinue, s we tk a break.
select v. 挑选；选拔 The teachers will select ne student frm each class fr the cmpetitin.