Within a PBL unit we want students to discover learning as they work to answer a question or solve a challenge. To accomplish this, we may have to fight the urge to spend a ton of time building background knowledge before we begin! I remember a point in my career when I would give an anticipatory set to determine the knowledge my students already had on a topic. Based on that data, I would curate videos, books, mini-lessons, and *ahem* worksheets that I would use in my instruction so that they would have all of the information necessary to complete a project after I had told them everything they needed to know. I would even put up the learning goal on the board before hand. Does this scenario sound familiar...

Science Learning Goal: Plants depend on water and light to grow.

Cue lots of direct instruction about how plants depend on water and light to grow.

End of Unit Science Challenge: Plan and conduct an investigation to determine if plants need sunlight and water to grow. 

Me: Ok kiddos...How could we test this?

Them: Let's put one plant in the window and one in the closet and see which grows better!

Me: Great and which variable is that testing?

Them: Light!

Me: Great! Now I want you to record your hypothesis in your science notebooks. What do you think will be the outcome of each test?

Them: My hypothesis is that the plant in the window will grow and the one on the closet will die.

Ugh. And still every time I'd have kids tell me the plant in the closet would grow better.

Here's the deal. What if we just started with the challenge? What if the scenario went a little more like this:

Science Challenge: Plan and conduct an investigation to determine if plants need sunlight and water to grow. 

Me: Ok... so given this challenge... what do you already know or think you know?

Them: "Plants grow outside." "They can grow inside too!" "My mom has a fancy light that she puts on her plants inside to make them grow better." "We have a plant in the corner of our living room that is growing." "Plants still live at night!" "Isn't it dark in Alaska a lot? Are there plants there?" "We had a drought last year and the grass died." "I don't think the grass died, because it started to grow again after it rained." "Well the plant in my grandma's living room died because the soil was dry." "I think cactus can grow without water. Or maybe with a little water. Does it ever rain in the desert?"

Me: Hmmm... interesting thoughts. What are some things that we need to know if we are going to plan an investigation to determine if plants need sunlight and water to grow?

Them: "Are we going to use real plants?" "What kind of plants?" "Where could put them?" "What is an investigation?" "Can we test water and sunlight together?"

Me: Those are some great starting thoughts. I can answer a couple of them right now. An investigation is..... Now, what resources might use to learn more about our wonderings?

Them: "We could look at a gardening magazine, my grandma has a lot!" "The internet, we could search for plant websites." "In the library I saw a book about flowers and trees."

Me: This sounds like a great start. We will come back to this chart throughout our project to continue adding what we've learned, what we need to know, and what resources can help us find more information. Let's get started!

This is a much better entry point to the exact same (real) second grade NGSS standard.

We don't want to always give away the prize of uncovering learning by telling kids exactly what they are going to do in the beginning. I've heard others describe this as someone giving you a beautifully wrapped for your birthday and shouting "It's a !" before you can open it.

That said, we do want students to have a bit of prior experience and knowledge to hang their caps on as they start a project. We want to them to have an understanding that plants are things that grow, and that they grow under a variety of conditions. Their goal is to determine what conditions are best - through investigating!

Your role as a PBL is not to

• feed all of the facts to them by the spoonful
• preplan investigations
• curate all of the resources students will need (but to have a few on hand to get started is a good idea)
• be the deliver of knowledge
• be the sole source of information.

Instead, the goal is for students to hear a challenge, and think "Hmmmm.. that reminds me of... and makes me wonder..."