Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 415 · 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 steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) reading the message
2. 2.⚖️ 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) True (b) False
3. 3.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
5. 5.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
6. 6.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) turmeric powder (d) white paper
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
9. 9.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
10. 10.True or false: writing the message is a job for an adult. (a) True (b) False
11. 11.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
12. 12.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a cotton bud (d) a magnet
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) turmeric powder
15. 15.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
16. 16.🔮 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
17. 17.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
18. 18.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
19. 19.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
20. 20.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
21. 21.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a battery cell
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
24. 24.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) reading the message (d) writing the message
25. 25.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) writing the message
26. 26.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
27. 27.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) lemon juice (d) yeast
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
30. 30.True or false: yeast is needed for the secret lemon message. (a) False (b) True
31. 31.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
33. 33.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
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 measure it (b) we change it (c) we keep it the same
35. 35.⚖️ 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 same paper (c) how dark the writing is (d) the kind of juice
36. 36.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) an adult with an iron (d) a battery cell
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.🧺 Do we need a cotton bud 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) a mirror (b) an adult with an iron (c) a cotton bud (d) white paper
40. 40.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed

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