Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 670 · 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.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
2. 2.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
6. 6.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
7. 7.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the iron setting
9. 9.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
10. 10.True or false: yeast is needed for the secret lemon message. (a) False (b) True
11. 11.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a magnet (c) white paper (d) a small bowl
14. 14.⚖️ 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) False (b) True
15. 15.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
17. 17.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) putting the iron away (d) plugging in the iron
18. 18.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
19. 19.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) letting the paper dry
21. 21.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
22. 22.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) a mirror (d) yeast
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
26. 26.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
27. 27.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
28. 28.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
29. 29.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a mirror (d) white paper
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a mirror (d) white paper
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) an adult with an iron (d) white paper
33. 33.⚖️ 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 iron setting (c) how dark the writing is (d) the same cotton bud
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a mirror (d) white paper
36. 36.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
37. 37.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
38. 38.True or false: cutting the lemon is a job a child can do. (a) True (b) False
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a magnet (d) white paper
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) yeast (d) turmeric powder

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