Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 680 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the same cotton bud (c) the iron setting (d) how dark the writing is
2. 2.True or false: white paper is needed for the secret lemon message. (a) True (b) False
3. 3.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
4. 4.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
7. 7.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) dipping the cotton bud
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
10. 10.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) lemon juice (d) turmeric powder
13. 13.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) an adult with an iron (d) a balloon
14. 14.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the same paper (d) the ironing time
17. 17.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) a small bowl (d) white paper
20. 20.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
21. 21.🍋 Which of these steps is a job a child can do? (a) reading the message (b) putting the iron away (c) ironing the paper (d) plugging in the iron
22. 22.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
23. 23.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
24. 24.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) ironing the paper (d) plugging in the iron
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) turmeric powder
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) yeast (d) an adult with an iron
27. 27.⚖️ 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
28. 28.True or false: cutting the lemon is a job a child can do. (a) True (b) False
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a balloon (d) white paper
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the ironing time
34. 34.⚖️ 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
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
36. 36.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a small bowl (d) a cotton bud
39. 39.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
40. 40.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed

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