Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 877 · 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: yeast is not needed for the secret lemon message. (a) False (b) True
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) a mirror (d) turmeric powder
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) the kind of juice (d) how dark the writing is
4. 4.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) writing the message
5. 5.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
6. 6.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
7. 7.⚖️ 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
8. 8.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
9. 9.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) white paper
11. 11.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a mirror (d) turmeric powder
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
16. 16.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) letting the paper dry
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) a small bowl (d) an adult with an iron
18. 18.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a small bowl (d) a balloon
19. 19.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
20. 20.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a small bowl (d) turmeric powder
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
24. 24.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) writing the message
25. 25.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
26. 26.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same paper (c) the ironing time (d) how dark the writing is
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a mirror (d) white paper
29. 29.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) yeast
32. 32.⚖️ 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 measure it (c) we change it
33. 33.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a balloon (d) a cotton bud
35. 35.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
38. 38.True or false: reading the message is a job a child can do. (a) False (b) True
39. 39.🔮 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
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) a mirror

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