Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 776 · 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) dipping the cotton bud (c) cutting the lemon (d) ironing the paper
2. 2.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
3. 3.⚖️ 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) the same paper (c) how dark the writing is
4. 4.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
5. 5.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) plugging in the iron
6. 6.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) putting the iron away (d) ironing the paper
7. 7.True or false: putting the iron away is a job for an adult. (a) False (b) True
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a battery cell (d) lemon juice
9. 9.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ 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
11. 11.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
14. 14.True or false: reading the message is a job a child can do. (a) False (b) True
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a small bowl (d) a battery cell
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) an adult with an iron (d) a cotton bud
18. 18.⚖️ 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
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a magnet (d) a cotton bud
21. 21.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
22. 22.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a magnet (d) a mirror
23. 23.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) ironing the paper (d) reading the message
24. 24.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
25. 25.🛟 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
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) turmeric powder (d) an adult with an iron
28. 28.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) writing the message
29. 29.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) writing the message
30. 30.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
32. 32.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
33. 33.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
34. 34.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
35. 35.⚖️ 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
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
37. 37.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) yeast (d) a cotton bud
39. 39.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
40. 40.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green

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