Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 716 · 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.True or false: ironing the paper is a job a child can do. (a) False (b) True
2. 2.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
4. 4.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
5. 5.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) ironing the paper (c) putting the iron away (d) plugging in the iron
6. 6.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
7. 7.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) putting the iron away (d) dipping the cotton bud
8. 8.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a magnet (c) turmeric powder (d) a mirror
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a battery cell (d) a cotton bud
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) white paper (d) a cotton bud
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) physical (d) magnetic
12. 12.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) an adult with an iron (d) white paper
14. 14.⚖️ 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
15. 15.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
16. 16.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
17. 17.⚖️ 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 change it (c) we keep it the same
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
19. 19.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
20. 20.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
21. 21.True or false: ironing the paper is a job for an adult. (a) False (b) True
22. 22.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
23. 23.True or false: yeast is needed for the secret lemon message. (a) False (b) True
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
25. 25.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
26. 26.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) yeast (d) an adult with an iron
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
29. 29.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) reading the message (d) letting the paper dry
30. 30.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) cutting the lemon
31. 31.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
32. 32.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
33. 33.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
35. 35.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
36. 36.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
38. 38.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ 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) the iron setting (c) the kind of juice (d) the same paper
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a balloon (c) a mirror (d) yeast

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