Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 823 · 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.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a battery cell
2. 2.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) writing the message
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a mirror (d) a cotton bud
6. 6.🧺 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) lemon juice (d) turmeric powder
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
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 kind of juice (b) the ironing time (c) how dark the writing is (d) the same paper
9. 9.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
11. 11.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) turmeric powder (d) yeast
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) a magnet (d) lemon juice
13. 13.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
14. 14.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) reading the message
15. 15.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) white paper (d) lemon juice
18. 18.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
19. 19.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) putting the iron away (d) ironing the paper
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
21. 21.⚖️ 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 same cotton bud
22. 22.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
24. 24.🧺 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) a magnet (d) a cotton bud
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
26. 26.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) plugging in the iron (d) putting the iron away
28. 28.⚖️ 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 keep it the same (c) we change it
29. 29.True or false: plugging in the iron is a job for an adult. (a) True (b) False
30. 30.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a balloon (c) lemon juice (d) white paper
32. 32.True or false: plugging in the iron is a job a child can do. (a) True (b) False
33. 33.True or false: cutting the lemon is a job for an adult. (a) True (b) False
34. 34.⚖️ 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
35. 35.⚖️ 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 same paper
36. 36.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) physical (d) musical
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a battery cell (d) a magnet
38. 38.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) an adult with an iron (d) lemon juice
40. 40.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper

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