Da Niu hurriedly said, "You don't need to climb trees." ”

Li Shimin thought about it and said to Li Junxian: "Then cutting down the tree is also a good way." ”

Da Niu said: "There is no need to cut down trees, this is the homework assigned by our teacher." ”

"Homework?"

"Hmm!"

Da Niu said: "The teacher said that you can measure the height of this tree without touching it. ”

Li Shimin said with a smile: "If you want to measure the height of this tree, how can you not touch it." ”

The bull ordered a group of children to bring a stick one foot long.

Li Shimin looked curious, saw that the group of children looked at the sun, stood the stick next to the big tree and began to measure the shadow of the tree and the shadow of the stick.

After a while, Li Shimin asked, "Did you measure it out?" ”

"It's been calculated, there are three out of three." Da Niu replied.

"Three feet and three ......"

Li Shimin was surprised in his heart how this group of children was calculated, and Li Shimin said to Li Junxian: "You climb up and try to measure it." ”

Da Niu handed Li Junxian a rope and said, "This rope is about six zhang long, you can hang it on the top of the tree." ”

Li Junxian climbed onto the trunk of the tree in a few moments and hung one end of the rope on the top of the tree.

The rope stuck to the trunk of the tree all the way to the ground, Fang Xuanling tore off the excess rope that fell on the ground, measured it with his hand and said: "Your Majesty, this rope was originally six zhang long and now there are two and a half zhang left, this group of children is right, it should be three zhang three." ”

Li Junxian had already jumped from the tree.

Li Shimin once again thought back to what this group of children had done.

I wondered how they could use the shadow of a stick and the shadow of a tree to calculate the height of a tree so easily.

"Xuan Ling, do you know what Li Zheng teaches the children in Jingyang Academy?"

Fang Xuanling replied: "I don't know, but I heard Kong Yingda say that it seems to be some truth and mathematics." ”

"Mathematical ......"

Li Shimin asked Da Niu, "How did you calculate it?" ”

Da Niu grinned: "It's actually very simple. ”

Simple? Li Shimin smiled bitterly, why he couldn't understand the simple things of a group of children.

Da Niu explained: "At the same time, the angle of sunlight is the same, and the angle of the stick in the horizontal position and the tree is also the same, the length of the shadow of a long stick is one zhang, and the shadow of the tree is three zhang three, so the height of the tree can be obtained by proportional relationship." ”

After listening to Fang Xuanling and clarifying his thoughts, he understood that it was indeed a very ingenious method.

Li Shimin asked Da Niu again, "You said this is very simple, so will Li Zheng teach you more difficult?" ”

"Of course." Da Niu said with some pride: "Dare to ask when the sun is closest to us." ”

Li Shimin smiled: "Of course, it is in the morning and evening, when the sun is at its highest. ”

Da Niu asked again, "Then why is the sun hottest at noon?" ”

This one......

Li Shimin's smile stopped abruptly.

Just as I wanted to ask, Da Niu had already run away with a group of children.

Li Shimin and Fang Xuanling were stunned.

The sun is at its highest in the morning and hottest at noon......

Li Shimin thought about it for a long time and didn't figure it out, and said with a dark face: "What Li Zheng teaches children all day long is some evil and crooked ways. ”

Fang Xuanling smiled awkwardly.

What does a ten-year-old do?

Maybe those ten-year-old children in Chang'an can't even count them all, and the children here already have such a complicated calculation?

A few people walked around the village again and found a large box every other section of the road, on which were written three large garbage bins.

No wonder the village is so clean, it turns out that they have a special box for garbage, and there is a sign next to the garbage bin, which says please don't litter.

It's very particular when you look at it.

Thinking of the mess in some streets in Chang'an now, Li Shimin felt that this thing could also be placed in Chang'an, and he benefited a lot from this trip.

Fang Xuanling saw a large patch of rice planted by the riverbank.

"Your Majesty, these ears of rice have bent and drooped down the rhizomes."

Li Shimin also looked at these ears of rice, the grains were very full, and he was surprised to see that there were fish swimming in the ditches of the rice fields.

Most people in Chang'an eat millet rice, and rice is indeed grown, but it is very small and too difficult to cultivate.

As early as the Wude period, some people said that the rice seeds from the south were brought to Chang'an for planting.

I also tried many times that the harvest was not very good.

After that, I gave up.

Li Shimin looked at these ears of rice, and it was the first time he had seen such full ears of rice.

It doesn't seem to be the same as the ears of rice I've seen before.

On a high slope in the distance of Jingyang County, Li Shimin, Fang Xuanling and Li Junxian stood in the distance and watched Li Tai and Li Zheng.

One fat and one thin sat by the river and ate, so comfortable.

Li Tai ate the corn and said: "This corn is still delicious when cooked, soft and glutinous and sweet." ”

"Li Zheng."

Hearing the familiar call, Li Zheng looked back, "Brother, why are you here?" ”

Li Shimin smiled and said, "Come and see you, how are you doing recently?" ”

"It's all good."

Li Tai hadn't turned around yet, and when he heard this familiar voice, he was stunned in place and didn't dare to turn back.

"It's been a long time, brother, why is your complexion getting worse and worse."

Li Shimin smiled and said, "I've been worrying a lot lately. ”

Li Zheng said to Li Tai: "Fatty! You come to meet, this is the old brother I told you before. ”

Li Shimin's smile stiffened on his face, Li Zheng, this kid, is so called my son?

Even if Li Tai is relatively fat, no one dares to call him that on weekdays.

Li Tai turned his head mechanically, saw Fang Xuanling, and saw Li Junxian.

Look at the smile of his father and Li Zheng.

"Qingque, why don't you speak?" Li Shimin asked.

Li Tai covered his forehead, Li Zheng called his father and emperor?

This is not right, when did my father and Li Zheng become commensurate with the brothers?

So what should I call Li Zheng?

If Li Zheng is going to marry Lizhi, then the future generations will not be chaotic.

Li Tai covered his forehead painfully and said, "This generation seems to be a bit messy, let the sons and daughters sort it out first." ”

Son-in-law?

Li Zheng pulled Li Tai to the side and asked in a low voice, "What son?" ”

Li Tai also dragged Li Zheng to death, and said with a worried face: "Li Zheng! What is your relationship with my father? ”

"Your father!"

Li Zheng almost screamed.

Li Shimin stepped forward and said, "What are you two muttering? ”

Again and again retreated to keep a distance from Li Shimin, Li Zheng said: "I'm a little messy now, you let me sort it out." ”

Li Tai thought for a long time, his expression seemed to be enlightened, and he patted his thigh and pointed at Li Zheng and said loudly: "Li Zheng! I understand, you and my father have already planted incense, cut off the head of the chicken, and worshiped the son as brothers, right! ”