Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 509 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a cotton bud (d) an adult with an iron
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same paper (c) the kind of juice
3. 3.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a battery cell (d) white paper
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
6. 6.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) white paper (c) a magnet (d) a balloon
8. 8.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
9. 9.True or false: putting the iron away is a job a child can do. (a) True (b) False
10. 10.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
11. 11.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the iron setting (d) the ironing time
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
16. 16.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
17. 17.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
18. 18.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same paper
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) an adult with an iron (d) white paper
21. 21.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
23. 23.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) ironing the paper
24. 24.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
25. 25.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a small bowl (c) a balloon (d) a battery cell
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) cutting the lemon (d) plugging in the iron
28. 28.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
29. 29.True or false: writing the message is a job for an adult. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) turmeric powder (d) white paper
33. 33.True or false: ironing the paper is a job a child can do. (a) False (b) True
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a small bowl (d) an adult with an iron
35. 35.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
37. 37.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) letting the paper dry
38. 38.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
39. 39.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a battery cell (d) a cotton bud

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